1 /*
   2  * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2023, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "classfile/classLoaderData.inline.hpp"
  28 #include "classfile/classLoaderDataGraph.hpp"
  29 #include "classfile/javaClasses.inline.hpp"
  30 #include "classfile/symbolTable.hpp"
  31 #include "classfile/vmClasses.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "gc/shared/gcLocker.hpp"
  34 #include "gc/shared/gcVMOperations.hpp"
  35 #include "gc/shared/workerThread.hpp"
  36 #include "jfr/jfrEvents.hpp"
  37 #include "jvm.h"
  38 #include "memory/allocation.inline.hpp"
  39 #include "memory/resourceArea.hpp"
  40 #include "memory/universe.hpp"
  41 #include "oops/fieldStreams.inline.hpp"
  42 #include "oops/klass.inline.hpp"
  43 #include "oops/objArrayKlass.hpp"
  44 #include "oops/objArrayOop.inline.hpp"
  45 #include "oops/flatArrayKlass.hpp"
  46 #include "oops/flatArrayOop.inline.hpp"
  47 #include "oops/oop.inline.hpp"
  48 #include "oops/typeArrayOop.inline.hpp"
  49 #include "runtime/continuationWrapper.inline.hpp"
  50 #include "runtime/fieldDescriptor.inline.hpp"
  51 #include "runtime/frame.inline.hpp"
  52 #include "runtime/handles.inline.hpp"
  53 #include "runtime/javaCalls.hpp"
  54 #include "runtime/javaThread.inline.hpp"
  55 #include "runtime/jniHandles.hpp"
  56 #include "runtime/os.hpp"
  57 #include "runtime/threads.hpp"
  58 #include "runtime/threadSMR.hpp"
  59 #include "runtime/vframe.hpp"
  60 #include "runtime/vmOperations.hpp"
  61 #include "runtime/vmThread.hpp"
  62 #include "runtime/timerTrace.hpp"
  63 #include "services/heapDumper.hpp"
  64 #include "services/heapDumperCompression.hpp"
  65 #include "services/threadService.hpp"
  66 #include "utilities/checkedCast.hpp"
  67 #include "utilities/macros.hpp"
  68 #include "utilities/ostream.hpp"
  69 #ifdef LINUX
  70 #include "os_linux.hpp"
  71 #endif
  72 
  73 /*
  74  * HPROF binary format - description copied from:
  75  *   src/share/demo/jvmti/hprof/hprof_io.c
  76  *
  77  *
  78  *  header    "JAVA PROFILE 1.0.2" (0-terminated)
  79  *
  80  *  u4        size of identifiers. Identifiers are used to represent
  81  *            UTF8 strings, objects, stack traces, etc. They usually
  82  *            have the same size as host pointers.
  83  * u4         high word
  84  * u4         low word    number of milliseconds since 0:00 GMT, 1/1/70
  85  * [record]*  a sequence of records.
  86  *
  87  *
  88  * Record format:
  89  *
  90  * u1         a TAG denoting the type of the record
  91  * u4         number of *microseconds* since the time stamp in the
  92  *            header. (wraps around in a little more than an hour)
  93  * u4         number of bytes *remaining* in the record. Note that
  94  *            this number excludes the tag and the length field itself.
  95  * [u1]*      BODY of the record (a sequence of bytes)
  96  *
  97  *
  98  * The following TAGs are supported:
  99  *
 100  * TAG           BODY       notes
 101  *----------------------------------------------------------
 102  * HPROF_UTF8               a UTF8-encoded name
 103  *
 104  *               id         name ID
 105  *               [u1]*      UTF8 characters (no trailing zero)
 106  *
 107  * HPROF_LOAD_CLASS         a newly loaded class
 108  *
 109  *                u4        class serial number (> 0)
 110  *                id        class object ID
 111  *                u4        stack trace serial number
 112  *                id        class name ID
 113  *
 114  * HPROF_UNLOAD_CLASS       an unloading class
 115  *
 116  *                u4        class serial_number
 117  *
 118  * HPROF_FRAME              a Java stack frame
 119  *
 120  *                id        stack frame ID
 121  *                id        method name ID
 122  *                id        method signature ID
 123  *                id        source file name ID
 124  *                u4        class serial number
 125  *                i4        line number. >0: normal
 126  *                                       -1: unknown
 127  *                                       -2: compiled method
 128  *                                       -3: native method
 129  *
 130  * HPROF_TRACE              a Java stack trace
 131  *
 132  *               u4         stack trace serial number
 133  *               u4         thread serial number
 134  *               u4         number of frames
 135  *               [id]*      stack frame IDs
 136  *
 137  *
 138  * HPROF_ALLOC_SITES        a set of heap allocation sites, obtained after GC
 139  *
 140  *               u2         flags 0x0001: incremental vs. complete
 141  *                                0x0002: sorted by allocation vs. live
 142  *                                0x0004: whether to force a GC
 143  *               u4         cutoff ratio
 144  *               u4         total live bytes
 145  *               u4         total live instances
 146  *               u8         total bytes allocated
 147  *               u8         total instances allocated
 148  *               u4         number of sites that follow
 149  *               [u1        is_array: 0:  normal object
 150  *                                    2:  object array
 151  *                                    4:  boolean array
 152  *                                    5:  char array
 153  *                                    6:  float array
 154  *                                    7:  double array
 155  *                                    8:  byte array
 156  *                                    9:  short array
 157  *                                    10: int array
 158  *                                    11: long array
 159  *                u4        class serial number (may be zero during startup)
 160  *                u4        stack trace serial number
 161  *                u4        number of bytes alive
 162  *                u4        number of instances alive
 163  *                u4        number of bytes allocated
 164  *                u4]*      number of instance allocated
 165  *
 166  * HPROF_START_THREAD       a newly started thread.
 167  *
 168  *               u4         thread serial number (> 0)
 169  *               id         thread object ID
 170  *               u4         stack trace serial number
 171  *               id         thread name ID
 172  *               id         thread group name ID
 173  *               id         thread group parent name ID
 174  *
 175  * HPROF_END_THREAD         a terminating thread.
 176  *
 177  *               u4         thread serial number
 178  *
 179  * HPROF_HEAP_SUMMARY       heap summary
 180  *
 181  *               u4         total live bytes
 182  *               u4         total live instances
 183  *               u8         total bytes allocated
 184  *               u8         total instances allocated
 185  *
 186  * HPROF_HEAP_DUMP          denote a heap dump
 187  *
 188  *               [heap dump sub-records]*
 189  *
 190  *                          There are four kinds of heap dump sub-records:
 191  *
 192  *               u1         sub-record type
 193  *
 194  *               HPROF_GC_ROOT_UNKNOWN         unknown root
 195  *
 196  *                          id         object ID
 197  *
 198  *               HPROF_GC_ROOT_THREAD_OBJ      thread object
 199  *
 200  *                          id         thread object ID  (may be 0 for a
 201  *                                     thread newly attached through JNI)
 202  *                          u4         thread sequence number
 203  *                          u4         stack trace sequence number
 204  *
 205  *               HPROF_GC_ROOT_JNI_GLOBAL      JNI global ref root
 206  *
 207  *                          id         object ID
 208  *                          id         JNI global ref ID
 209  *
 210  *               HPROF_GC_ROOT_JNI_LOCAL       JNI local ref
 211  *
 212  *                          id         object ID
 213  *                          u4         thread serial number
 214  *                          u4         frame # in stack trace (-1 for empty)
 215  *
 216  *               HPROF_GC_ROOT_JAVA_FRAME      Java stack frame
 217  *
 218  *                          id         object ID
 219  *                          u4         thread serial number
 220  *                          u4         frame # in stack trace (-1 for empty)
 221  *
 222  *               HPROF_GC_ROOT_NATIVE_STACK    Native stack
 223  *
 224  *                          id         object ID
 225  *                          u4         thread serial number
 226  *
 227  *               HPROF_GC_ROOT_STICKY_CLASS    System class
 228  *
 229  *                          id         object ID
 230  *
 231  *               HPROF_GC_ROOT_THREAD_BLOCK    Reference from thread block
 232  *
 233  *                          id         object ID
 234  *                          u4         thread serial number
 235  *
 236  *               HPROF_GC_ROOT_MONITOR_USED    Busy monitor
 237  *
 238  *                          id         object ID
 239  *
 240  *               HPROF_GC_CLASS_DUMP           dump of a class object
 241  *
 242  *                          id         class object ID
 243  *                          u4         stack trace serial number
 244  *                          id         super class object ID
 245  *                          id         class loader object ID
 246  *                          id         signers object ID
 247  *                          id         protection domain object ID
 248  *                          id         reserved
 249  *                          id         reserved
 250  *
 251  *                          u4         instance size (in bytes)
 252  *
 253  *                          u2         size of constant pool
 254  *                          [u2,       constant pool index,
 255  *                           ty,       type
 256  *                                     2:  object
 257  *                                     4:  boolean
 258  *                                     5:  char
 259  *                                     6:  float
 260  *                                     7:  double
 261  *                                     8:  byte
 262  *                                     9:  short
 263  *                                     10: int
 264  *                                     11: long
 265  *                           vl]*      and value
 266  *
 267  *                          u2         number of static fields
 268  *                          [id,       static field name,
 269  *                           ty,       type,
 270  *                           vl]*      and value
 271  *
 272  *                          u2         number of inst. fields (not inc. super)
 273  *                          [id,       instance field name,
 274  *                           ty]*      type
 275  *
 276  *               HPROF_GC_INSTANCE_DUMP        dump of a normal object
 277  *
 278  *                          id         object ID
 279  *                          u4         stack trace serial number
 280  *                          id         class object ID
 281  *                          u4         number of bytes that follow
 282  *                          [vl]*      instance field values (class, followed
 283  *                                     by super, super's super ...)
 284  *
 285  *               HPROF_GC_OBJ_ARRAY_DUMP       dump of an object array
 286  *
 287  *                          id         array object ID
 288  *                          u4         stack trace serial number
 289  *                          u4         number of elements
 290  *                          id         array class ID
 291  *                          [id]*      elements
 292  *
 293  *               HPROF_GC_PRIM_ARRAY_DUMP      dump of a primitive array
 294  *
 295  *                          id         array object ID
 296  *                          u4         stack trace serial number
 297  *                          u4         number of elements
 298  *                          u1         element type
 299  *                                     4:  boolean array
 300  *                                     5:  char array
 301  *                                     6:  float array
 302  *                                     7:  double array
 303  *                                     8:  byte array
 304  *                                     9:  short array
 305  *                                     10: int array
 306  *                                     11: long array
 307  *                          [u1]*      elements
 308  *
 309  * HPROF_CPU_SAMPLES        a set of sample traces of running threads
 310  *
 311  *                u4        total number of samples
 312  *                u4        # of traces
 313  *               [u4        # of samples
 314  *                u4]*      stack trace serial number
 315  *
 316  * HPROF_CONTROL_SETTINGS   the settings of on/off switches
 317  *
 318  *                u4        0x00000001: alloc traces on/off
 319  *                          0x00000002: cpu sampling on/off
 320  *                u2        stack trace depth
 321  *
 322  * HPROF_FLAT_ARRAYS        list of flat arrays
 323  *
 324  *               [flat array sub-records]*
 325  *
 326  *               HPROF_FLAT_ARRAY      flat array
 327  *
 328  *                          id         array object ID (dumped as HPROF_GC_PRIM_ARRAY_DUMP)
 329  *                          id         element class ID (dumped by HPROF_GC_CLASS_DUMP)
 330  *
 331  * HPROF_INLINED_FIELDS     decribes inlined fields
 332  *
 333  *               [class with inlined fields sub-records]*
 334  *
 335  *               HPROF_CLASS_WITH_INLINED_FIELDS
 336  *
 337  *                          id         class ID (dumped as HPROF_GC_CLASS_DUMP)
 338  *
 339  *                          u2         number of instance inlined fields (not including super)
 340  *                          [u2,       inlined field index,
 341  *                           u2,       synthetic field count,
 342  *                           id,       original field name,
 343  *                           id]*      inlined field class ID (dumped by HPROF_GC_CLASS_DUMP)
 344  *
 345  * When the header is "JAVA PROFILE 1.0.2" a heap dump can optionally
 346  * be generated as a sequence of heap dump segments. This sequence is
 347  * terminated by an end record. The additional tags allowed by format
 348  * "JAVA PROFILE 1.0.2" are:
 349  *
 350  * HPROF_HEAP_DUMP_SEGMENT  denote a heap dump segment
 351  *
 352  *               [heap dump sub-records]*
 353  *               The same sub-record types allowed by HPROF_HEAP_DUMP
 354  *
 355  * HPROF_HEAP_DUMP_END      denotes the end of a heap dump
 356  *
 357  */
 358 
 359 
 360 // HPROF tags
 361 
 362 enum hprofTag : u1 {
 363   // top-level records
 364   HPROF_UTF8                    = 0x01,
 365   HPROF_LOAD_CLASS              = 0x02,
 366   HPROF_UNLOAD_CLASS            = 0x03,
 367   HPROF_FRAME                   = 0x04,
 368   HPROF_TRACE                   = 0x05,
 369   HPROF_ALLOC_SITES             = 0x06,
 370   HPROF_HEAP_SUMMARY            = 0x07,
 371   HPROF_START_THREAD            = 0x0A,
 372   HPROF_END_THREAD              = 0x0B,
 373   HPROF_HEAP_DUMP               = 0x0C,
 374   HPROF_CPU_SAMPLES             = 0x0D,
 375   HPROF_CONTROL_SETTINGS        = 0x0E,
 376 
 377   // 1.0.2 record types
 378   HPROF_HEAP_DUMP_SEGMENT       = 0x1C,
 379   HPROF_HEAP_DUMP_END           = 0x2C,
 380 
 381   // inlined object support
 382   HPROF_FLAT_ARRAYS             = 0x12,
 383   HPROF_INLINED_FIELDS          = 0x13,
 384   // inlined object subrecords
 385   HPROF_FLAT_ARRAY                  = 0x01,
 386   HPROF_CLASS_WITH_INLINED_FIELDS   = 0x01,
 387 
 388   // field types
 389   HPROF_ARRAY_OBJECT            = 0x01,
 390   HPROF_NORMAL_OBJECT           = 0x02,
 391   HPROF_BOOLEAN                 = 0x04,
 392   HPROF_CHAR                    = 0x05,
 393   HPROF_FLOAT                   = 0x06,
 394   HPROF_DOUBLE                  = 0x07,
 395   HPROF_BYTE                    = 0x08,
 396   HPROF_SHORT                   = 0x09,
 397   HPROF_INT                     = 0x0A,
 398   HPROF_LONG                    = 0x0B,
 399 
 400   // data-dump sub-records
 401   HPROF_GC_ROOT_UNKNOWN         = 0xFF,
 402   HPROF_GC_ROOT_JNI_GLOBAL      = 0x01,
 403   HPROF_GC_ROOT_JNI_LOCAL       = 0x02,
 404   HPROF_GC_ROOT_JAVA_FRAME      = 0x03,
 405   HPROF_GC_ROOT_NATIVE_STACK    = 0x04,
 406   HPROF_GC_ROOT_STICKY_CLASS    = 0x05,
 407   HPROF_GC_ROOT_THREAD_BLOCK    = 0x06,
 408   HPROF_GC_ROOT_MONITOR_USED    = 0x07,
 409   HPROF_GC_ROOT_THREAD_OBJ      = 0x08,
 410   HPROF_GC_CLASS_DUMP           = 0x20,
 411   HPROF_GC_INSTANCE_DUMP        = 0x21,
 412   HPROF_GC_OBJ_ARRAY_DUMP       = 0x22,
 413   HPROF_GC_PRIM_ARRAY_DUMP      = 0x23
 414 };
 415 
 416 // Default stack trace ID (used for dummy HPROF_TRACE record)
 417 enum {
 418   STACK_TRACE_ID = 1,
 419   INITIAL_CLASS_COUNT = 200
 420 };
 421 
 422 
 423 class AbstractDumpWriter;
 424 
 425 class InlinedObjects {
 426 
 427   struct ClassInlinedFields {
 428     const Klass *klass;
 429     uintx base_index;   // base index of the inlined field names (1st field has index base_index+1).
 430     ClassInlinedFields(const Klass *klass = nullptr, uintx base_index = 0) : klass(klass), base_index(base_index) {}
 431 
 432     // For GrowableArray::find_sorted().
 433     static int compare(const ClassInlinedFields& a, const ClassInlinedFields& b) {
 434       return a.klass - b.klass;
 435     }
 436     // For GrowableArray::sort().
 437     static int compare(ClassInlinedFields* a, ClassInlinedFields* b) {
 438       return compare(*a, *b);
 439     }
 440   };
 441 
 442   uintx _min_string_id;
 443   uintx _max_string_id;
 444 
 445   GrowableArray<ClassInlinedFields> *_inlined_field_map;
 446 
 447   // counters for classes with inlined fields and for the fields
 448   int _classes_count;
 449   int _inlined_fields_count;
 450 
 451   static InlinedObjects *_instance;
 452 
 453   static void inlined_field_names_callback(InlinedObjects* _this, const Klass *klass, uintx base_index, int count);
 454 
 455   GrowableArray<oop> *_flat_arrays;
 456 
 457 public:
 458   InlinedObjects()
 459     : _min_string_id(0), _max_string_id(0),
 460     _inlined_field_map(nullptr),
 461     _classes_count(0), _inlined_fields_count(0),
 462     _flat_arrays(nullptr) {
 463   }
 464 
 465   static InlinedObjects* get_instance() {
 466     return _instance;
 467   }
 468 
 469   void init();
 470   void release();
 471 
 472   void dump_inlined_field_names(AbstractDumpWriter *writer);
 473 
 474   uintx get_base_index_for(Klass* k);
 475   uintx get_next_string_id(uintx id);
 476 
 477   void dump_classed_with_inlined_fields(AbstractDumpWriter* writer);
 478 
 479   void add_flat_array(oop array);
 480   void dump_flat_arrays(AbstractDumpWriter* writer);
 481 
 482 };
 483 
 484 InlinedObjects *InlinedObjects::_instance = nullptr;
 485 
 486 
 487 // Supports I/O operations for a dump
 488 // Base class for dump and parallel dump
 489 class AbstractDumpWriter : public CHeapObj<mtInternal> {
 490  protected:
 491   enum {
 492     io_buffer_max_size = 1*M,
 493     dump_segment_header_size = 9
 494   };
 495 
 496   char* _buffer;    // internal buffer
 497   size_t _size;
 498   size_t _pos;
 499 
 500   bool _in_dump_segment; // Are we currently in a dump segment?
 501   bool _is_huge_sub_record; // Are we writing a sub-record larger than the buffer size?
 502   DEBUG_ONLY(size_t _sub_record_left;) // The bytes not written for the current sub-record.
 503   DEBUG_ONLY(bool _sub_record_ended;) // True if we have called the end_sub_record().
 504 
 505   char* buffer() const                          { return _buffer; }
 506   size_t buffer_size() const                    { return _size; }
 507   void set_position(size_t pos)                 { _pos = pos; }
 508 
 509   // Can be called if we have enough room in the buffer.
 510   void write_fast(const void* s, size_t len);
 511 
 512   // Returns true if we have enough room in the buffer for 'len' bytes.
 513   bool can_write_fast(size_t len);
 514 
 515   void write_address(address a);
 516 
 517  public:
 518   AbstractDumpWriter() :
 519     _buffer(nullptr),
 520     _size(io_buffer_max_size),
 521     _pos(0),
 522     _in_dump_segment(false) { }
 523 
 524   // Total number of bytes written to the disk
 525   virtual julong bytes_written() const = 0;
 526   // Return non-null if error occurred
 527   virtual char const* error() const = 0;
 528 
 529   size_t position() const                       { return _pos; }
 530   // writer functions
 531   virtual void write_raw(const void* s, size_t len);
 532   void write_u1(u1 x);
 533   void write_u2(u2 x);
 534   void write_u4(u4 x);
 535   void write_u8(u8 x);
 536   void write_objectID(oop o);
 537   void write_rootID(oop* p);
 538   void write_symbolID(Symbol* o);
 539   void write_classID(Klass* k);
 540   void write_id(u4 x);
 541 
 542   // Start a new sub-record. Starts a new heap dump segment if needed.
 543   void start_sub_record(u1 tag, u4 len);
 544   // Ends the current sub-record.
 545   void end_sub_record();
 546   // Finishes the current dump segment if not already finished.
 547   void finish_dump_segment();
 548   // Flush internal buffer to persistent storage
 549   virtual void flush() = 0;
 550 };
 551 
 552 void AbstractDumpWriter::write_fast(const void* s, size_t len) {
 553   assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
 554   assert(buffer_size() - position() >= len, "Must fit");
 555   debug_only(_sub_record_left -= len);
 556   memcpy(buffer() + position(), s, len);
 557   set_position(position() + len);
 558 }
 559 
 560 bool AbstractDumpWriter::can_write_fast(size_t len) {
 561   return buffer_size() - position() >= len;
 562 }
 563 
 564 // write raw bytes
 565 void AbstractDumpWriter::write_raw(const void* s, size_t len) {
 566   assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
 567   debug_only(_sub_record_left -= len);
 568 
 569   // flush buffer to make room.
 570   while (len > buffer_size() - position()) {
 571     assert(!_in_dump_segment || _is_huge_sub_record,
 572            "Cannot overflow in non-huge sub-record.");
 573     size_t to_write = buffer_size() - position();
 574     memcpy(buffer() + position(), s, to_write);
 575     s = (void*) ((char*) s + to_write);
 576     len -= to_write;
 577     set_position(position() + to_write);
 578     flush();
 579   }
 580 
 581   memcpy(buffer() + position(), s, len);
 582   set_position(position() + len);
 583 }
 584 
 585 // Makes sure we inline the fast write into the write_u* functions. This is a big speedup.
 586 #define WRITE_KNOWN_TYPE(p, len) do { if (can_write_fast((len))) write_fast((p), (len)); \
 587                                       else write_raw((p), (len)); } while (0)
 588 
 589 void AbstractDumpWriter::write_u1(u1 x) {
 590   WRITE_KNOWN_TYPE(&x, 1);
 591 }
 592 
 593 void AbstractDumpWriter::write_u2(u2 x) {
 594   u2 v;
 595   Bytes::put_Java_u2((address)&v, x);
 596   WRITE_KNOWN_TYPE(&v, 2);
 597 }
 598 
 599 void AbstractDumpWriter::write_u4(u4 x) {
 600   u4 v;
 601   Bytes::put_Java_u4((address)&v, x);
 602   WRITE_KNOWN_TYPE(&v, 4);
 603 }
 604 
 605 void AbstractDumpWriter::write_u8(u8 x) {
 606   u8 v;
 607   Bytes::put_Java_u8((address)&v, x);
 608   WRITE_KNOWN_TYPE(&v, 8);
 609 }
 610 
 611 void AbstractDumpWriter::write_address(address a) {
 612 #ifdef _LP64
 613   write_u8((u8)a);
 614 #else
 615   write_u4((u4)a);
 616 #endif
 617 }
 618 
 619 void AbstractDumpWriter::write_objectID(oop o) {
 620   write_address(cast_from_oop<address>(o));
 621 }
 622 
 623 void AbstractDumpWriter::write_rootID(oop* p) {
 624   write_address((address)p);
 625 }
 626 
 627 void AbstractDumpWriter::write_symbolID(Symbol* s) {
 628   write_address((address)((uintptr_t)s));
 629 }
 630 
 631 void AbstractDumpWriter::write_id(u4 x) {
 632 #ifdef _LP64
 633   write_u8((u8) x);
 634 #else
 635   write_u4(x);
 636 #endif
 637 }
 638 
 639 // We use java mirror as the class ID
 640 void AbstractDumpWriter::write_classID(Klass* k) {
 641   write_objectID(k->java_mirror());
 642 }
 643 
 644 void AbstractDumpWriter::finish_dump_segment() {
 645   if (_in_dump_segment) {
 646     assert(_sub_record_left == 0, "Last sub-record not written completely");
 647     assert(_sub_record_ended, "sub-record must have ended");
 648 
 649     // Fix up the dump segment length if we haven't written a huge sub-record last
 650     // (in which case the segment length was already set to the correct value initially).
 651     if (!_is_huge_sub_record) {
 652       assert(position() > dump_segment_header_size, "Dump segment should have some content");
 653       Bytes::put_Java_u4((address) (buffer() + 5),
 654                          (u4) (position() - dump_segment_header_size));
 655     } else {
 656       // Finish process huge sub record
 657       // Set _is_huge_sub_record to false so the parallel dump writer can flush data to file.
 658       _is_huge_sub_record = false;
 659     }
 660 
 661     _in_dump_segment = false;
 662     flush();
 663   }
 664 }
 665 
 666 void AbstractDumpWriter::start_sub_record(u1 tag, u4 len) {
 667   if (!_in_dump_segment) {
 668     if (position() > 0) {
 669       flush();
 670     }
 671 
 672     assert(position() == 0 && buffer_size() > dump_segment_header_size, "Must be at the start");
 673 
 674     write_u1(HPROF_HEAP_DUMP_SEGMENT);
 675     write_u4(0); // timestamp
 676     // Will be fixed up later if we add more sub-records.  If this is a huge sub-record,
 677     // this is already the correct length, since we don't add more sub-records.
 678     write_u4(len);
 679     assert(Bytes::get_Java_u4((address)(buffer() + 5)) == len, "Inconsistent size!");
 680     _in_dump_segment = true;
 681     _is_huge_sub_record = len > buffer_size() - dump_segment_header_size;
 682   } else if (_is_huge_sub_record || (len > buffer_size() - position())) {
 683     // This object will not fit in completely or the last sub-record was huge.
 684     // Finish the current segment and try again.
 685     finish_dump_segment();
 686     start_sub_record(tag, len);
 687 
 688     return;
 689   }
 690 
 691   debug_only(_sub_record_left = len);
 692   debug_only(_sub_record_ended = false);
 693 
 694   write_u1(tag);
 695 }
 696 
 697 void AbstractDumpWriter::end_sub_record() {
 698   assert(_in_dump_segment, "must be in dump segment");
 699   assert(_sub_record_left == 0, "sub-record not written completely");
 700   assert(!_sub_record_ended, "Must not have ended yet");
 701   debug_only(_sub_record_ended = true);
 702 }
 703 
 704 // Supports I/O operations for a dump
 705 
 706 class DumpWriter : public AbstractDumpWriter {
 707 private:
 708   FileWriter* _writer;
 709   AbstractCompressor* _compressor;
 710   size_t _bytes_written;
 711   char* _error;
 712   // Compression support
 713   char* _out_buffer;
 714   size_t _out_size;
 715   size_t _out_pos;
 716   char* _tmp_buffer;
 717   size_t _tmp_size;
 718 
 719 private:
 720   void do_compress();
 721 
 722 public:
 723   DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor);
 724   ~DumpWriter();
 725   julong bytes_written() const override        { return (julong) _bytes_written; }
 726   void set_bytes_written(julong bytes_written) { _bytes_written = bytes_written; }
 727   char const* error() const override           { return _error; }
 728   void set_error(const char* error)            { _error = (char*)error; }
 729   bool has_error() const                       { return _error != nullptr; }
 730   const char* get_file_path() const            { return _writer->get_file_path(); }
 731   AbstractCompressor* compressor()             { return _compressor; }
 732   void set_compressor(AbstractCompressor* p)   { _compressor = p; }
 733   bool is_overwrite() const                    { return _writer->is_overwrite(); }
 734   int get_fd() const                           { return _writer->get_fd(); }
 735 
 736   void flush() override;
 737 };
 738 
 739 DumpWriter::DumpWriter(const char* path, bool overwrite, AbstractCompressor* compressor) :
 740   AbstractDumpWriter(),
 741   _writer(new (std::nothrow) FileWriter(path, overwrite)),
 742   _compressor(compressor),
 743   _bytes_written(0),
 744   _error(nullptr),
 745   _out_buffer(nullptr),
 746   _out_size(0),
 747   _out_pos(0),
 748   _tmp_buffer(nullptr),
 749   _tmp_size(0) {
 750   _error = (char*)_writer->open_writer();
 751   if (_error == nullptr) {
 752     _buffer = (char*)os::malloc(io_buffer_max_size, mtInternal);
 753     if (compressor != nullptr) {
 754       _error = (char*)_compressor->init(io_buffer_max_size, &_out_size, &_tmp_size);
 755       if (_error == nullptr) {
 756         if (_out_size > 0) {
 757           _out_buffer = (char*)os::malloc(_out_size, mtInternal);
 758         }
 759         if (_tmp_size > 0) {
 760           _tmp_buffer = (char*)os::malloc(_tmp_size, mtInternal);
 761         }
 762       }
 763     }
 764   }
 765   // initialize internal buffer
 766   _pos = 0;
 767   _size = io_buffer_max_size;
 768 }
 769 
 770 DumpWriter::~DumpWriter(){
 771   if (_buffer != nullptr) {
 772     os::free(_buffer);
 773   }
 774   if (_out_buffer != nullptr) {
 775     os::free(_out_buffer);
 776   }
 777   if (_tmp_buffer != nullptr) {
 778     os::free(_tmp_buffer);
 779   }
 780   if (_writer != NULL) {
 781     delete _writer;
 782   }
 783   _bytes_written = -1;
 784 }
 785 
 786 // flush any buffered bytes to the file
 787 void DumpWriter::flush() {
 788   if (_pos <= 0) {
 789     return;
 790   }
 791   if (has_error()) {
 792     _pos = 0;
 793     return;
 794   }
 795   char* result = nullptr;
 796   if (_compressor == nullptr) {
 797     result = (char*)_writer->write_buf(_buffer, _pos);
 798     _bytes_written += _pos;
 799   } else {
 800     do_compress();
 801     if (!has_error()) {
 802       result = (char*)_writer->write_buf(_out_buffer, _out_pos);
 803       _bytes_written += _out_pos;
 804     }
 805   }
 806   _pos = 0; // reset pos to make internal buffer available
 807 
 808   if (result != nullptr) {
 809     set_error(result);
 810   }
 811 }
 812 
 813 void DumpWriter::do_compress() {
 814   const char* msg = _compressor->compress(_buffer, _pos, _out_buffer, _out_size,
 815                                           _tmp_buffer, _tmp_size, &_out_pos);
 816 
 817   if (msg != nullptr) {
 818     set_error(msg);
 819   }
 820 }
 821 
 822 class DumperClassCacheTable;
 823 class DumperClassCacheTableEntry;
 824 
 825 // Support class with a collection of functions used when dumping the heap
 826 class DumperSupport : AllStatic {
 827  public:
 828 
 829   // write a header of the given type
 830   static void write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len);
 831 
 832   // returns hprof tag for the given type signature
 833   static hprofTag sig2tag(Symbol* sig);
 834   // returns hprof tag for the given basic type
 835   static hprofTag type2tag(BasicType type);
 836   // Returns the size of the data to write.
 837   static u4 sig2size(Symbol* sig);
 838 
 839   // calculates the total size of the all fields of the given class.
 840   static u4 instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry = nullptr);
 841 
 842   // dump a jfloat
 843   static void dump_float(AbstractDumpWriter* writer, jfloat f);
 844   // dump a jdouble
 845   static void dump_double(AbstractDumpWriter* writer, jdouble d);
 846   // dumps the raw value of the given field
 847   static void dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset);
 848   // returns the size of the static fields; also counts the static fields
 849   static u4 get_static_fields_size(InstanceKlass* ik, u2& field_count);
 850   // dumps static fields of the given class
 851   static void dump_static_fields(AbstractDumpWriter* writer, Klass* k);
 852   // dump the raw values of the instance fields of the given identity or inlined object;
 853   // for identity objects offset is 0 and 'klass' is o->klass(),
 854   // for inlined objects offset is the offset in the holder object, 'klass' is inlined object class
 855   static void dump_instance_fields(AbstractDumpWriter* writer, oop o, int offset, DumperClassCacheTable* class_cache, DumperClassCacheTableEntry* class_cache_entry);
 856   // dump the raw values of the instance fields of the given inlined object;
 857   // dump_instance_fields wrapper for inlined objects
 858   static void dump_inlined_object_fields(AbstractDumpWriter* writer, oop o, int offset, DumperClassCacheTable* class_cache, DumperClassCacheTableEntry* class_cache_entry);
 859 
 860   // get the count of the instance fields for a given class
 861   static u2 get_instance_fields_count(InstanceKlass* ik);
 862   // dumps the definition of the instance fields for a given class
 863   static void dump_instance_field_descriptors(AbstractDumpWriter* writer, InstanceKlass* k, uintx *inlined_fields_index = nullptr);
 864   // creates HPROF_GC_INSTANCE_DUMP record for the given object
 865   static void dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache);
 866   // creates HPROF_GC_CLASS_DUMP record for the given instance class
 867   static void dump_instance_class(AbstractDumpWriter* writer, Klass* k);
 868   // creates HPROF_GC_CLASS_DUMP record for a given array class
 869   static void dump_array_class(AbstractDumpWriter* writer, Klass* k);
 870 
 871   // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
 872   static void dump_object_array(AbstractDumpWriter* writer, objArrayOop array);
 873   // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given flat array
 874   static void dump_flat_array(AbstractDumpWriter* writer, flatArrayOop array, DumperClassCacheTable* class_cache);
 875   // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
 876   static void dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array);
 877   // create HPROF_FRAME record for the given method and bci
 878   static void dump_stack_frame(AbstractDumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci);
 879 
 880   // check if we need to truncate an array
 881   static int calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size);
 882   // extended version to dump flat arrays as primitive arrays;
 883   // type_size specifies size of the inlined objects.
 884   static int calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, int type_size, short header_size);
 885 
 886   // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
 887   static void end_of_dump(AbstractDumpWriter* writer);
 888 
 889   static oop mask_dormant_archived_object(oop o) {
 890     if (o != nullptr && o->klass()->java_mirror() == nullptr) {
 891       // Ignore this object since the corresponding java mirror is not loaded.
 892       // Might be a dormant archive object.
 893       return nullptr;
 894     } else {
 895       return o;
 896     }
 897   }
 898 
 899   // helper methods for inlined fields.
 900   static bool is_inlined_field(const fieldDescriptor& fld) {
 901     return fld.is_flat();
 902   }
 903   static InlineKlass* get_inlined_field_klass(const fieldDescriptor& fld) {
 904     assert(is_inlined_field(fld), "must be inlined field");
 905     InstanceKlass* holder_klass = fld.field_holder();
 906     return InlineKlass::cast(holder_klass->get_inline_type_field_klass(fld.index()));
 907   }
 908 };
 909 
 910 // Hash table of klasses to the klass metadata. This should greatly improve the
 911 // hash dumping performance. This hash table is supposed to be used by a single
 912 // thread only.
 913 //
 914 class DumperClassCacheTableEntry : public CHeapObj<mtServiceability> {
 915   friend class DumperClassCacheTable;
 916 private:
 917   GrowableArray<char> _sigs_start;
 918   GrowableArray<int> _offsets;
 919   GrowableArray<InlineKlass*> _inline_klasses;
 920   u4 _instance_size;
 921   int _entries;
 922 
 923 public:
 924   DumperClassCacheTableEntry() : _instance_size(0), _entries(0) {};
 925 
 926   int field_count()             { return _entries; }
 927   char sig_start(int field_idx) { return _sigs_start.at(field_idx); }
 928   void push_sig_start_inlined() { _sigs_start.push('Q'); }
 929   bool is_inlined(int field_idx){ return _sigs_start.at(field_idx) == 'Q'; }
 930   InlineKlass* inline_klass(int field_idx) { assert(is_inlined(field_idx), "Not inlined"); return _inline_klasses.at(field_idx); }
 931   int offset(int field_idx)     { return _offsets.at(field_idx); }
 932   u4 instance_size()            { return _instance_size; }
 933 };
 934 
 935 class DumperClassCacheTable {
 936 private:
 937   // ResourceHashtable SIZE is specified at compile time so we
 938   // use 1031 which is the first prime after 1024.
 939   static constexpr size_t TABLE_SIZE = 1031;
 940 
 941   // Maintain the cache for N classes. This limits memory footprint
 942   // impact, regardless of how many classes we have in the dump.
 943   // This also improves look up performance by keeping the statically
 944   // sized table from overloading.
 945   static constexpr int CACHE_TOP = 256;
 946 
 947   typedef ResourceHashtable<InstanceKlass*, DumperClassCacheTableEntry*,
 948                             TABLE_SIZE, AnyObj::C_HEAP, mtServiceability> PtrTable;
 949   PtrTable* _ptrs;
 950 
 951   // Single-slot cache to handle the major case of objects of the same
 952   // class back-to-back, e.g. from T[].
 953   InstanceKlass* _last_ik;
 954   DumperClassCacheTableEntry* _last_entry;
 955 
 956   void unlink_all(PtrTable* table) {
 957     class CleanupEntry: StackObj {
 958     public:
 959       bool do_entry(InstanceKlass*& key, DumperClassCacheTableEntry*& entry) {
 960         delete entry;
 961         return true;
 962       }
 963     } cleanup;
 964     table->unlink(&cleanup);
 965   }
 966 
 967 public:
 968   DumperClassCacheTableEntry* lookup_or_create(InstanceKlass* ik) {
 969     if (_last_ik == ik) {
 970       return _last_entry;
 971     }
 972 
 973     DumperClassCacheTableEntry* entry;
 974     DumperClassCacheTableEntry** from_cache = _ptrs->get(ik);
 975     if (from_cache == nullptr) {
 976       entry = new DumperClassCacheTableEntry();
 977       for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
 978         if (!fld.access_flags().is_static()) {
 979           InlineKlass* inlineKlass = nullptr;
 980           if (DumperSupport::is_inlined_field(fld.field_descriptor())) {
 981             inlineKlass = DumperSupport::get_inlined_field_klass(fld.field_descriptor());
 982             entry->push_sig_start_inlined();
 983             entry->_instance_size += DumperSupport::instance_size(inlineKlass);
 984           } else {
 985             Symbol* sig = fld.signature();
 986             entry->_sigs_start.push(sig->char_at(0));
 987             entry->_instance_size += DumperSupport::sig2size(sig);
 988           }
 989           entry->_inline_klasses.push(inlineKlass);
 990           entry->_offsets.push(fld.offset());
 991           entry->_entries++;
 992         }
 993       }
 994 
 995       if (_ptrs->number_of_entries() >= CACHE_TOP) {
 996         // We do not track the individual hit rates for table entries.
 997         // Purge the entire table, and let the cache catch up with new
 998         // distribution.
 999         unlink_all(_ptrs);
1000       }
1001 
1002       _ptrs->put(ik, entry);
1003     } else {
1004       entry = *from_cache;
1005     }
1006 
1007     // Remember for single-slot cache.
1008     _last_ik = ik;
1009     _last_entry = entry;
1010 
1011     return entry;
1012   }
1013 
1014   DumperClassCacheTable() : _ptrs(new (mtServiceability) PtrTable), _last_ik(nullptr), _last_entry(nullptr) {}
1015 
1016   ~DumperClassCacheTable() {
1017     unlink_all(_ptrs);
1018     delete _ptrs;
1019   }
1020 };
1021 
1022 // write a header of the given type
1023 void DumperSupport:: write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len) {
1024   writer->write_u1(tag);
1025   writer->write_u4(0);                  // current ticks
1026   writer->write_u4(len);
1027 }
1028 
1029 // returns hprof tag for the given type signature
1030 hprofTag DumperSupport::sig2tag(Symbol* sig) {
1031   switch (sig->char_at(0)) {
1032     case JVM_SIGNATURE_CLASS    : return HPROF_NORMAL_OBJECT;
1033     case JVM_SIGNATURE_ARRAY    : return HPROF_NORMAL_OBJECT;
1034     case JVM_SIGNATURE_BYTE     : return HPROF_BYTE;
1035     case JVM_SIGNATURE_CHAR     : return HPROF_CHAR;
1036     case JVM_SIGNATURE_FLOAT    : return HPROF_FLOAT;
1037     case JVM_SIGNATURE_DOUBLE   : return HPROF_DOUBLE;
1038     case JVM_SIGNATURE_INT      : return HPROF_INT;
1039     case JVM_SIGNATURE_LONG     : return HPROF_LONG;
1040     case JVM_SIGNATURE_SHORT    : return HPROF_SHORT;
1041     case JVM_SIGNATURE_BOOLEAN  : return HPROF_BOOLEAN;
1042     default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
1043   }
1044 }
1045 
1046 hprofTag DumperSupport::type2tag(BasicType type) {
1047   switch (type) {
1048     case T_BYTE     : return HPROF_BYTE;
1049     case T_CHAR     : return HPROF_CHAR;
1050     case T_FLOAT    : return HPROF_FLOAT;
1051     case T_DOUBLE   : return HPROF_DOUBLE;
1052     case T_INT      : return HPROF_INT;
1053     case T_LONG     : return HPROF_LONG;
1054     case T_SHORT    : return HPROF_SHORT;
1055     case T_BOOLEAN  : return HPROF_BOOLEAN;
1056     default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
1057   }
1058 }
1059 
1060 u4 DumperSupport::sig2size(Symbol* sig) {
1061   switch (sig->char_at(0)) {
1062     case JVM_SIGNATURE_CLASS:
1063     case JVM_SIGNATURE_ARRAY: return sizeof(address);
1064     case JVM_SIGNATURE_BOOLEAN:
1065     case JVM_SIGNATURE_BYTE: return 1;
1066     case JVM_SIGNATURE_SHORT:
1067     case JVM_SIGNATURE_CHAR: return 2;
1068     case JVM_SIGNATURE_INT:
1069     case JVM_SIGNATURE_FLOAT: return 4;
1070     case JVM_SIGNATURE_LONG:
1071     case JVM_SIGNATURE_DOUBLE: return 8;
1072     default: ShouldNotReachHere(); /* to shut up compiler */ return 0;
1073   }
1074 }
1075 
1076 template<typename T, typename F> T bit_cast(F from) { // replace with the real thing when we can use c++20
1077   T to;
1078   static_assert(sizeof(to) == sizeof(from), "must be of the same size");
1079   memcpy(&to, &from, sizeof(to));
1080   return to;
1081 }
1082 
1083 // dump a jfloat
1084 void DumperSupport::dump_float(AbstractDumpWriter* writer, jfloat f) {
1085   if (g_isnan(f)) {
1086     writer->write_u4(0x7fc00000); // collapsing NaNs
1087   } else {
1088     writer->write_u4(bit_cast<u4>(f));
1089   }
1090 }
1091 
1092 // dump a jdouble
1093 void DumperSupport::dump_double(AbstractDumpWriter* writer, jdouble d) {
1094   if (g_isnan(d)) {
1095     writer->write_u8(0x7ff80000ull << 32); // collapsing NaNs
1096   } else {
1097     writer->write_u8(bit_cast<u8>(d));
1098   }
1099 }
1100 
1101 
1102 // dumps the raw value of the given field
1103 void DumperSupport::dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset) {
1104   switch (type) {
1105     case JVM_SIGNATURE_CLASS :
1106     case JVM_SIGNATURE_ARRAY : {
1107       oop o = obj->obj_field_access<ON_UNKNOWN_OOP_REF | AS_NO_KEEPALIVE>(offset);
1108       if (o != nullptr && log_is_enabled(Debug, cds, heap) && mask_dormant_archived_object(o) == nullptr) {
1109         ResourceMark rm;
1110         log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)",
1111                              p2i(o), o->klass()->external_name(),
1112                              p2i(obj), obj->klass()->external_name());
1113       }
1114       o = mask_dormant_archived_object(o);
1115       assert(oopDesc::is_oop_or_null(o), "Expected an oop or nullptr at " PTR_FORMAT, p2i(o));
1116       writer->write_objectID(o);
1117       break;
1118     }
1119     case JVM_SIGNATURE_BYTE : {
1120       jbyte b = obj->byte_field(offset);
1121       writer->write_u1(b);
1122       break;
1123     }
1124     case JVM_SIGNATURE_CHAR : {
1125       jchar c = obj->char_field(offset);
1126       writer->write_u2(c);
1127       break;
1128     }
1129     case JVM_SIGNATURE_SHORT : {
1130       jshort s = obj->short_field(offset);
1131       writer->write_u2(s);
1132       break;
1133     }
1134     case JVM_SIGNATURE_FLOAT : {
1135       jfloat f = obj->float_field(offset);
1136       dump_float(writer, f);
1137       break;
1138     }
1139     case JVM_SIGNATURE_DOUBLE : {
1140       jdouble d = obj->double_field(offset);
1141       dump_double(writer, d);
1142       break;
1143     }
1144     case JVM_SIGNATURE_INT : {
1145       jint i = obj->int_field(offset);
1146       writer->write_u4(i);
1147       break;
1148     }
1149     case JVM_SIGNATURE_LONG : {
1150       jlong l = obj->long_field(offset);
1151       writer->write_u8(l);
1152       break;
1153     }
1154     case JVM_SIGNATURE_BOOLEAN : {
1155       jboolean b = obj->bool_field(offset);
1156       writer->write_u1(b);
1157       break;
1158     }
1159     default : {
1160       ShouldNotReachHere();
1161       break;
1162     }
1163   }
1164 }
1165 
1166 // calculates the total size of the all fields of the given class.
1167 u4 DumperSupport::instance_size(InstanceKlass* ik, DumperClassCacheTableEntry* class_cache_entry) {
1168   if (class_cache_entry != nullptr) {
1169     return class_cache_entry->instance_size();
1170   } else {
1171     u4 size = 0;
1172     for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
1173       if (!fld.access_flags().is_static()) {
1174         if (is_inlined_field(fld.field_descriptor())) {
1175           size += instance_size(get_inlined_field_klass(fld.field_descriptor()));
1176         } else {
1177           size += sig2size(fld.signature());
1178         }
1179       }
1180     }
1181     return size;
1182   }
1183 }
1184 
1185 u4 DumperSupport::get_static_fields_size(InstanceKlass* ik, u2& field_count) {
1186   field_count = 0;
1187   u4 size = 0;
1188 
1189   for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) {
1190     if (fldc.access_flags().is_static()) {
1191       assert(!is_inlined_field(fldc.field_descriptor()), "static fields cannot be inlined");
1192 
1193       field_count++;
1194       size += sig2size(fldc.signature());
1195     }
1196   }
1197 
1198   // Add in resolved_references which is referenced by the cpCache
1199   // The resolved_references is an array per InstanceKlass holding the
1200   // strings and other oops resolved from the constant pool.
1201   oop resolved_references = ik->constants()->resolved_references_or_null();
1202   if (resolved_references != nullptr) {
1203     field_count++;
1204     size += sizeof(address);
1205 
1206     // Add in the resolved_references of the used previous versions of the class
1207     // in the case of RedefineClasses
1208     InstanceKlass* prev = ik->previous_versions();
1209     while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
1210       field_count++;
1211       size += sizeof(address);
1212       prev = prev->previous_versions();
1213     }
1214   }
1215 
1216   // We write the value itself plus a name and a one byte type tag per field.
1217   return checked_cast<u4>(size + field_count * (sizeof(address) + 1));
1218 }
1219 
1220 // dumps static fields of the given class
1221 void DumperSupport::dump_static_fields(AbstractDumpWriter* writer, Klass* k) {
1222   InstanceKlass* ik = InstanceKlass::cast(k);
1223 
1224   // dump the field descriptors and raw values
1225   for (JavaFieldStream fld(ik); !fld.done(); fld.next()) {
1226     if (fld.access_flags().is_static()) {
1227       assert(!is_inlined_field(fld.field_descriptor()), "static fields cannot be inlined");
1228 
1229       Symbol* sig = fld.signature();
1230 
1231       writer->write_symbolID(fld.name());   // name
1232       writer->write_u1(sig2tag(sig));       // type
1233 
1234       // value
1235       dump_field_value(writer, sig->char_at(0), ik->java_mirror(), fld.offset());
1236     }
1237   }
1238 
1239   // Add resolved_references for each class that has them
1240   oop resolved_references = ik->constants()->resolved_references_or_null();
1241   if (resolved_references != nullptr) {
1242     writer->write_symbolID(vmSymbols::resolved_references_name());  // name
1243     writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
1244     writer->write_objectID(resolved_references);
1245 
1246     // Also write any previous versions
1247     InstanceKlass* prev = ik->previous_versions();
1248     while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
1249       writer->write_symbolID(vmSymbols::resolved_references_name());  // name
1250       writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
1251       writer->write_objectID(prev->constants()->resolved_references());
1252       prev = prev->previous_versions();
1253     }
1254   }
1255 }
1256 
1257 // dump the raw values of the instance fields of the given identity or inlined object;
1258 // for identity objects offset is 0 and 'klass' is o->klass(),
1259 // for inlined objects offset is the offset in the holder object, 'klass' is inlined object class.
1260 void DumperSupport::dump_instance_fields(AbstractDumpWriter* writer, oop o, int offset, DumperClassCacheTable* class_cache, DumperClassCacheTableEntry* class_cache_entry) {
1261   assert(class_cache_entry != nullptr, "Pre-condition: must be provided");
1262   for (int idx = 0; idx < class_cache_entry->field_count(); idx++) {
1263     if (class_cache_entry->is_inlined(idx)) {
1264       InlineKlass* field_klass = class_cache_entry->inline_klass(idx);
1265       int fields_offset = offset + (class_cache_entry->offset(idx) - field_klass->first_field_offset());
1266       DumperClassCacheTableEntry* inline_class_cache_entry = class_cache->lookup_or_create(field_klass);
1267       dump_inlined_object_fields(writer, o, fields_offset, class_cache, inline_class_cache_entry);
1268     } else {
1269       dump_field_value(writer, class_cache_entry->sig_start(idx), o, class_cache_entry->offset(idx));
1270     }
1271   }
1272 }
1273 
1274 void DumperSupport::dump_inlined_object_fields(AbstractDumpWriter* writer, oop o, int offset, DumperClassCacheTable* class_cache, DumperClassCacheTableEntry* class_cache_entry) {
1275   // the object is inlined, so all its fields are stored without headers.
1276   dump_instance_fields(writer, o, offset, class_cache, class_cache_entry);
1277 }
1278 
1279 // gets the count of the instance fields for a given class
1280 u2 DumperSupport::get_instance_fields_count(InstanceKlass* ik) {
1281   u2 field_count = 0;
1282 
1283   for (JavaFieldStream fldc(ik); !fldc.done(); fldc.next()) {
1284     if (!fldc.access_flags().is_static()) {
1285       if (is_inlined_field(fldc.field_descriptor())) {
1286         // add "synthetic" fields for inlined fields.
1287         field_count += get_instance_fields_count(get_inlined_field_klass(fldc.field_descriptor()));
1288       } else {
1289         field_count++;
1290       }
1291     }
1292   }
1293 
1294   return field_count;
1295 }
1296 
1297 // dumps the definition of the instance fields for a given class
1298 // inlined_fields_id is not-nullptr for inlined fields (to get synthetic field name IDs
1299 // by using InlinedObjects::get_next_string_id()).
1300 void DumperSupport::dump_instance_field_descriptors(AbstractDumpWriter* writer, InstanceKlass* ik, uintx* inlined_fields_id) {
1301   // inlined_fields_id != nullptr means ik is a class of inlined field.
1302   // Inlined field id pointer for this class; lazyly initialized
1303   // if the class has inlined field(s) and the caller didn't provide inlined_fields_id.
1304   uintx *this_klass_inlined_fields_id = inlined_fields_id;
1305   uintx inlined_id = 0;
1306 
1307   // dump the field descriptors
1308   for (JavaFieldStream fld(ik); !fld.done(); fld.next()) {
1309     if (!fld.access_flags().is_static()) {
1310       if (is_inlined_field(fld.field_descriptor())) {
1311         // dump "synthetic" fields for inlined fields.
1312         if (this_klass_inlined_fields_id == nullptr) {
1313           inlined_id = InlinedObjects::get_instance()->get_base_index_for(ik);
1314           this_klass_inlined_fields_id = &inlined_id;
1315         }
1316         dump_instance_field_descriptors(writer, get_inlined_field_klass(fld.field_descriptor()), this_klass_inlined_fields_id);
1317       } else {
1318         Symbol* sig = fld.signature();
1319         Symbol* name = nullptr;
1320         // Use inlined_fields_id provided by caller.
1321         if (inlined_fields_id != nullptr) {
1322           uintx name_id = InlinedObjects::get_instance()->get_next_string_id(*inlined_fields_id);
1323 
1324           // name_id == 0 is returned on error. use original field signature.
1325           if (name_id != 0) {
1326             *inlined_fields_id = name_id;
1327             name = reinterpret_cast<Symbol*>(name_id);
1328           }
1329         }
1330         if (name == nullptr) {
1331           name = fld.name();
1332         }
1333 
1334         writer->write_symbolID(name);         // name
1335         writer->write_u1(sig2tag(sig));       // type
1336       }
1337     }
1338   }
1339 }
1340 
1341 // creates HPROF_GC_INSTANCE_DUMP record for the given object
1342 void DumperSupport::dump_instance(AbstractDumpWriter* writer, oop o, DumperClassCacheTable* class_cache) {
1343   InstanceKlass* ik = InstanceKlass::cast(o->klass());
1344 
1345   DumperClassCacheTableEntry* cache_entry = class_cache->lookup_or_create(ik);
1346 
1347   u4 is = instance_size(ik, cache_entry);
1348   u4 size = 1 + sizeof(address) + 4 + sizeof(address) + 4 + is;
1349 
1350   writer->start_sub_record(HPROF_GC_INSTANCE_DUMP, size);
1351   writer->write_objectID(o);
1352   writer->write_u4(STACK_TRACE_ID);
1353 
1354   // class ID
1355   writer->write_classID(ik);
1356 
1357   // number of bytes that follow
1358   writer->write_u4(is);
1359 
1360   // field values
1361   dump_instance_fields(writer, o, 0, class_cache, cache_entry);
1362 
1363   writer->end_sub_record();
1364 }
1365 
1366 // creates HPROF_GC_CLASS_DUMP record for the given instance class
1367 void DumperSupport::dump_instance_class(AbstractDumpWriter* writer, Klass* k) {
1368   InstanceKlass* ik = InstanceKlass::cast(k);
1369 
1370   // We can safepoint and do a heap dump at a point where we have a Klass,
1371   // but no java mirror class has been setup for it. So we need to check
1372   // that the class is at least loaded, to avoid crash from a null mirror.
1373   if (!ik->is_loaded()) {
1374     return;
1375   }
1376 
1377   u2 static_fields_count = 0;
1378   u4 static_size = get_static_fields_size(ik, static_fields_count);
1379   u2 instance_fields_count = get_instance_fields_count(ik);
1380   u4 instance_fields_size = instance_fields_count * (sizeof(address) + 1);
1381   u4 size = checked_cast<u4>(1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + static_size + 2 + instance_fields_size);
1382 
1383   writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
1384 
1385   // class ID
1386   writer->write_classID(ik);
1387   writer->write_u4(STACK_TRACE_ID);
1388 
1389   // super class ID
1390   InstanceKlass* java_super = ik->java_super();
1391   if (java_super == nullptr) {
1392     writer->write_objectID(oop(nullptr));
1393   } else {
1394     writer->write_classID(java_super);
1395   }
1396 
1397   writer->write_objectID(ik->class_loader());
1398   writer->write_objectID(ik->signers());
1399   writer->write_objectID(ik->protection_domain());
1400 
1401   // reserved
1402   writer->write_objectID(oop(nullptr));
1403   writer->write_objectID(oop(nullptr));
1404 
1405   // instance size
1406   writer->write_u4(HeapWordSize * ik->size_helper());
1407 
1408   // size of constant pool - ignored by HAT 1.1
1409   writer->write_u2(0);
1410 
1411   // static fields
1412   writer->write_u2(static_fields_count);
1413   dump_static_fields(writer, ik);
1414 
1415   // description of instance fields
1416   writer->write_u2(instance_fields_count);
1417   dump_instance_field_descriptors(writer, ik);
1418 
1419   writer->end_sub_record();
1420 }
1421 
1422 // creates HPROF_GC_CLASS_DUMP record for the given array class
1423 void DumperSupport::dump_array_class(AbstractDumpWriter* writer, Klass* k) {
1424   InstanceKlass* ik = nullptr; // bottom class for object arrays, null for primitive type arrays
1425   if (k->is_objArray_klass()) {
1426     Klass *bk = ObjArrayKlass::cast(k)->bottom_klass();
1427     assert(bk != nullptr, "checking");
1428     if (bk->is_instance_klass()) {
1429       ik = InstanceKlass::cast(bk);
1430     }
1431   }
1432 
1433   u4 size = 1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + 2;
1434   writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
1435   writer->write_classID(k);
1436   writer->write_u4(STACK_TRACE_ID);
1437 
1438   // super class of array classes is java.lang.Object
1439   InstanceKlass* java_super = k->java_super();
1440   assert(java_super != nullptr, "checking");
1441   writer->write_classID(java_super);
1442 
1443   writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->class_loader());
1444   writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->signers());
1445   writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->protection_domain());
1446 
1447   writer->write_objectID(oop(nullptr));    // reserved
1448   writer->write_objectID(oop(nullptr));
1449   writer->write_u4(0);             // instance size
1450   writer->write_u2(0);             // constant pool
1451   writer->write_u2(0);             // static fields
1452   writer->write_u2(0);             // instance fields
1453 
1454   writer->end_sub_record();
1455 
1456 }
1457 
1458 // Hprof uses an u4 as record length field,
1459 // which means we need to truncate arrays that are too long.
1460 int DumperSupport::calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, int type_size, short header_size) {
1461   int length = array->length();
1462 
1463   size_t length_in_bytes = (size_t)length * type_size;
1464   uint max_bytes = max_juint - header_size;
1465 
1466   if (length_in_bytes > max_bytes) {
1467     length = max_bytes / type_size;
1468     length_in_bytes = (size_t)length * type_size;
1469 
1470     BasicType type = ArrayKlass::cast(array->klass())->element_type();
1471     warning("cannot dump array of type %s[] with length %d; truncating to length %d",
1472             type2name_tab[type], array->length(), length);
1473   }
1474   return length;
1475 }
1476 
1477 int DumperSupport::calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size) {
1478   BasicType type = ArrayKlass::cast(array->klass())->element_type();
1479   assert((type >= T_BOOLEAN && type <= T_OBJECT) || type == T_PRIMITIVE_OBJECT, "invalid array element type");
1480   int type_size;
1481   if (type == T_OBJECT) {
1482     type_size = sizeof(address);
1483   } else if (type == T_PRIMITIVE_OBJECT) {
1484       // TODO: FIXME
1485       fatal("Not supported yet"); // FIXME: JDK-8325678
1486   } else {
1487     type_size = type2aelembytes(type);
1488   }
1489 
1490   return calculate_array_max_length(writer, array, type_size, header_size);
1491 }
1492 
1493 // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
1494 void DumperSupport::dump_object_array(AbstractDumpWriter* writer, objArrayOop array) {
1495   // sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) + sizeof(classID)
1496   short header_size = 1 + 2 * 4 + 2 * sizeof(address);
1497   int length = calculate_array_max_length(writer, array, header_size);
1498   u4 size = checked_cast<u4>(header_size + length * sizeof(address));
1499 
1500   writer->start_sub_record(HPROF_GC_OBJ_ARRAY_DUMP, size);
1501   writer->write_objectID(array);
1502   writer->write_u4(STACK_TRACE_ID);
1503   writer->write_u4(length);
1504 
1505   // array class ID
1506   writer->write_classID(array->klass());
1507 
1508   // [id]* elements
1509   for (int index = 0; index < length; index++) {
1510     oop o = array->obj_at(index);
1511     if (o != nullptr && log_is_enabled(Debug, cds, heap) && mask_dormant_archived_object(o) == nullptr) {
1512       ResourceMark rm;
1513       log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)",
1514                            p2i(o), o->klass()->external_name(),
1515                            p2i(array), array->klass()->external_name());
1516     }
1517     o = mask_dormant_archived_object(o);
1518     writer->write_objectID(o);
1519   }
1520 
1521   writer->end_sub_record();
1522 }
1523 
1524 // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given flat array
1525 void DumperSupport::dump_flat_array(AbstractDumpWriter* writer, flatArrayOop array, DumperClassCacheTable* class_cache) {
1526   FlatArrayKlass* array_klass = FlatArrayKlass::cast(array->klass());
1527   InlineKlass* element_klass = array_klass->element_klass();
1528   int element_size = instance_size(element_klass);
1529   /*                          id         array object ID
1530    *                          u4         stack trace serial number
1531    *                          u4         number of elements
1532    *                          u1         element type
1533    */
1534   short header_size = 1 + sizeof(address) + 2 * 4 + 1;
1535 
1536   // TODO: use T_SHORT/T_INT/T_LONG if needed to avoid truncation
1537   BasicType type = T_BYTE;
1538   int type_size = type2aelembytes(type);
1539   int length = calculate_array_max_length(writer, array, element_size, header_size);
1540   u4 length_in_bytes = (u4)(length * element_size);
1541   u4 size = header_size + length_in_bytes;
1542 
1543   writer->start_sub_record(HPROF_GC_PRIM_ARRAY_DUMP, size);
1544   writer->write_objectID(array);
1545   writer->write_u4(STACK_TRACE_ID);
1546   // TODO: round up array length for T_SHORT/T_INT/T_LONG
1547   writer->write_u4(length * element_size);
1548   writer->write_u1(type2tag(type));
1549 
1550   for (int index = 0; index < length; index++) {
1551     // need offset in the holder to read inlined object. calculate it from flatArrayOop::value_at_addr()
1552     int offset = (int)((address)array->value_at_addr(index, array_klass->layout_helper())
1553                   - cast_from_oop<address>(array));
1554     DumperClassCacheTableEntry* class_cache_entry = class_cache->lookup_or_create(element_klass);
1555     dump_inlined_object_fields(writer, array, offset, class_cache, class_cache_entry);
1556   }
1557 
1558   // TODO: write padding bytes for T_SHORT/T_INT/T_LONG
1559 
1560   InlinedObjects::get_instance()->add_flat_array(array);
1561 
1562   writer->end_sub_record();
1563 }
1564 
1565 #define WRITE_ARRAY(Array, Type, Size, Length) \
1566   for (int i = 0; i < Length; i++) { writer->write_##Size((Size)Array->Type##_at(i)); }
1567 
1568 // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
1569 void DumperSupport::dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array) {
1570   BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1571   // 2 * sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID)
1572   short header_size = 2 * 1 + 2 * 4 + sizeof(address);
1573 
1574   int length = calculate_array_max_length(writer, array, header_size);
1575   int type_size = type2aelembytes(type);
1576   u4 length_in_bytes = (u4)length * type_size;
1577   u4 size = header_size + length_in_bytes;
1578 
1579   writer->start_sub_record(HPROF_GC_PRIM_ARRAY_DUMP, size);
1580   writer->write_objectID(array);
1581   writer->write_u4(STACK_TRACE_ID);
1582   writer->write_u4(length);
1583   writer->write_u1(type2tag(type));
1584 
1585   // nothing to copy
1586   if (length == 0) {
1587     writer->end_sub_record();
1588     return;
1589   }
1590 
1591   // If the byte ordering is big endian then we can copy most types directly
1592 
1593   switch (type) {
1594     case T_INT : {
1595       if (Endian::is_Java_byte_ordering_different()) {
1596         WRITE_ARRAY(array, int, u4, length);
1597       } else {
1598         writer->write_raw(array->int_at_addr(0), length_in_bytes);
1599       }
1600       break;
1601     }
1602     case T_BYTE : {
1603       writer->write_raw(array->byte_at_addr(0), length_in_bytes);
1604       break;
1605     }
1606     case T_CHAR : {
1607       if (Endian::is_Java_byte_ordering_different()) {
1608         WRITE_ARRAY(array, char, u2, length);
1609       } else {
1610         writer->write_raw(array->char_at_addr(0), length_in_bytes);
1611       }
1612       break;
1613     }
1614     case T_SHORT : {
1615       if (Endian::is_Java_byte_ordering_different()) {
1616         WRITE_ARRAY(array, short, u2, length);
1617       } else {
1618         writer->write_raw(array->short_at_addr(0), length_in_bytes);
1619       }
1620       break;
1621     }
1622     case T_BOOLEAN : {
1623       if (Endian::is_Java_byte_ordering_different()) {
1624         WRITE_ARRAY(array, bool, u1, length);
1625       } else {
1626         writer->write_raw(array->bool_at_addr(0), length_in_bytes);
1627       }
1628       break;
1629     }
1630     case T_LONG : {
1631       if (Endian::is_Java_byte_ordering_different()) {
1632         WRITE_ARRAY(array, long, u8, length);
1633       } else {
1634         writer->write_raw(array->long_at_addr(0), length_in_bytes);
1635       }
1636       break;
1637     }
1638 
1639     // handle float/doubles in a special value to ensure than NaNs are
1640     // written correctly. TO DO: Check if we can avoid this on processors that
1641     // use IEEE 754.
1642 
1643     case T_FLOAT : {
1644       for (int i = 0; i < length; i++) {
1645         dump_float(writer, array->float_at(i));
1646       }
1647       break;
1648     }
1649     case T_DOUBLE : {
1650       for (int i = 0; i < length; i++) {
1651         dump_double(writer, array->double_at(i));
1652       }
1653       break;
1654     }
1655     default : ShouldNotReachHere();
1656   }
1657 
1658   writer->end_sub_record();
1659 }
1660 
1661 // create a HPROF_FRAME record of the given Method* and bci
1662 void DumperSupport::dump_stack_frame(AbstractDumpWriter* writer,
1663                                      int frame_serial_num,
1664                                      int class_serial_num,
1665                                      Method* m,
1666                                      int bci) {
1667   int line_number;
1668   if (m->is_native()) {
1669     line_number = -3;  // native frame
1670   } else {
1671     line_number = m->line_number_from_bci(bci);
1672   }
1673 
1674   write_header(writer, HPROF_FRAME, 4*oopSize + 2*sizeof(u4));
1675   writer->write_id(frame_serial_num);               // frame serial number
1676   writer->write_symbolID(m->name());                // method's name
1677   writer->write_symbolID(m->signature());           // method's signature
1678 
1679   assert(m->method_holder()->is_instance_klass(), "not InstanceKlass");
1680   writer->write_symbolID(m->method_holder()->source_file_name());  // source file name
1681   writer->write_u4(class_serial_num);               // class serial number
1682   writer->write_u4((u4) line_number);               // line number
1683 }
1684 
1685 
1686 class InlinedFieldNameDumper : public LockedClassesDo {
1687 public:
1688   typedef void (*Callback)(InlinedObjects *owner, const Klass *klass, uintx base_index, int count);
1689 
1690 private:
1691   AbstractDumpWriter* _writer;
1692   InlinedObjects *_owner;
1693   Callback       _callback;
1694   uintx _index;
1695 
1696   void dump_inlined_field_names(GrowableArray<Symbol*>* super_names, Symbol* field_name, InlineKlass* klass) {
1697     super_names->push(field_name);
1698     for (HierarchicalFieldStream<JavaFieldStream> fld(klass); !fld.done(); fld.next()) {
1699       if (!fld.access_flags().is_static()) {
1700         if (DumperSupport::is_inlined_field(fld.field_descriptor())) {
1701           dump_inlined_field_names(super_names, fld.name(), DumperSupport::get_inlined_field_klass(fld.field_descriptor()));
1702         } else {
1703           // get next string ID.
1704           uintx next_index = _owner->get_next_string_id(_index);
1705           if (next_index == 0) {
1706             // something went wrong (overflow?)
1707             // stop generation; the rest of inlined objects will have original field names.
1708             return;
1709           }
1710           _index = next_index;
1711 
1712           // Calculate length.
1713           int len = fld.name()->utf8_length();
1714           for (GrowableArrayIterator<Symbol*> it = super_names->begin(); it != super_names->end(); ++it) {
1715             len += (*it)->utf8_length() + 1;    // +1 for ".".
1716           }
1717 
1718           DumperSupport::write_header(_writer, HPROF_UTF8, oopSize + len);
1719           _writer->write_symbolID(reinterpret_cast<Symbol*>(_index));
1720           // Write the string value.
1721           // 1) super_names.
1722           for (GrowableArrayIterator<Symbol*> it = super_names->begin(); it != super_names->end(); ++it) {
1723             _writer->write_raw((*it)->bytes(), (*it)->utf8_length());
1724             _writer->write_u1('.');
1725           }
1726           // 2) field name.
1727           _writer->write_raw(fld.name()->bytes(), fld.name()->utf8_length());
1728         }
1729       }
1730     }
1731     super_names->pop();
1732   }
1733 
1734   void dump_inlined_field_names(Symbol* field_name, InlineKlass* field_klass) {
1735     GrowableArray<Symbol*> super_names(4, mtServiceability);
1736     dump_inlined_field_names(&super_names, field_name, field_klass);
1737   }
1738 
1739 public:
1740   InlinedFieldNameDumper(AbstractDumpWriter* writer, InlinedObjects* owner, Callback callback)
1741     : _writer(writer), _owner(owner), _callback(callback), _index(0)  {
1742   }
1743 
1744   void do_klass(Klass* k) {
1745     if (!k->is_instance_klass()) {
1746       return;
1747     }
1748     InstanceKlass* ik = InstanceKlass::cast(k);
1749     // if (ik->has_inline_type_fields()) {
1750     //   return;
1751     // }
1752 
1753     uintx base_index = _index;
1754     int count = 0;
1755 
1756     for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
1757       if (!fld.access_flags().is_static()) {
1758         if (DumperSupport::is_inlined_field(fld.field_descriptor())) {
1759           dump_inlined_field_names(fld.name(), DumperSupport::get_inlined_field_klass(fld.field_descriptor()));
1760           count++;
1761         }
1762       }
1763     }
1764 
1765     if (count != 0) {
1766       _callback(_owner, k, base_index, count);
1767     }
1768   }
1769 };
1770 
1771 class InlinedFieldsDumper : public LockedClassesDo {
1772 private:
1773   AbstractDumpWriter* _writer;
1774 
1775 public:
1776   InlinedFieldsDumper(AbstractDumpWriter* writer) : _writer(writer) {}
1777 
1778   void do_klass(Klass* k) {
1779     if (!k->is_instance_klass()) {
1780       return;
1781     }
1782     InstanceKlass* ik = InstanceKlass::cast(k);
1783     // if (ik->has_inline_type_fields()) {
1784     //   return;
1785     // }
1786 
1787     // We can be at a point where java mirror does not exist yet.
1788     // So we need to check that the class is at least loaded, to avoid crash from a null mirror.
1789     if (!ik->is_loaded()) {
1790       return;
1791     }
1792 
1793     u2 inlined_count = 0;
1794     for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
1795       if (!fld.access_flags().is_static()) {
1796         if (DumperSupport::is_inlined_field(fld.field_descriptor())) {
1797           inlined_count++;
1798         }
1799       }
1800     }
1801     if (inlined_count != 0) {
1802       _writer->write_u1(HPROF_CLASS_WITH_INLINED_FIELDS);
1803 
1804       // class ID
1805       _writer->write_classID(ik);
1806       // number of inlined fields
1807       _writer->write_u2(inlined_count);
1808       u2 index = 0;
1809       for (HierarchicalFieldStream<JavaFieldStream> fld(ik); !fld.done(); fld.next()) {
1810         if (!fld.access_flags().is_static()) {
1811           if (DumperSupport::is_inlined_field(fld.field_descriptor())) {
1812             // inlined field index
1813             _writer->write_u2(index);
1814             // synthetic field count
1815             u2 field_count = DumperSupport::get_instance_fields_count(DumperSupport::get_inlined_field_klass(fld.field_descriptor()));
1816             _writer->write_u2(field_count);
1817             // original field name
1818             _writer->write_symbolID(fld.name());
1819             // inlined field class ID
1820             _writer->write_classID(DumperSupport::get_inlined_field_klass(fld.field_descriptor()));
1821 
1822             index += field_count;
1823           } else {
1824             index++;
1825           }
1826         }
1827       }
1828     }
1829   }
1830 };
1831 
1832 
1833 void InlinedObjects::init() {
1834   _instance = this;
1835 
1836   struct Closure : public SymbolClosure {
1837     uintx _min_id = max_uintx;
1838     uintx _max_id = 0;
1839     Closure() : _min_id(max_uintx), _max_id(0) {}
1840 
1841     void do_symbol(Symbol** p) {
1842       uintx val = reinterpret_cast<uintx>(*p);
1843       if (val < _min_id) {
1844         _min_id = val;
1845       }
1846       if (val > _max_id) {
1847         _max_id = val;
1848       }
1849     }
1850   } closure;
1851 
1852   SymbolTable::symbols_do(&closure);
1853 
1854   _min_string_id = closure._min_id;
1855   _max_string_id = closure._max_id;
1856 }
1857 
1858 void InlinedObjects::release() {
1859   _instance = nullptr;
1860 
1861   if (_inlined_field_map != nullptr) {
1862     delete _inlined_field_map;
1863     _inlined_field_map = nullptr;
1864   }
1865   if (_flat_arrays != nullptr) {
1866     delete _flat_arrays;
1867     _flat_arrays = nullptr;
1868   }
1869 }
1870 
1871 void InlinedObjects::inlined_field_names_callback(InlinedObjects* _this, const Klass* klass, uintx base_index, int count) {
1872   if (_this->_inlined_field_map == nullptr) {
1873     _this->_inlined_field_map = new (mtServiceability) GrowableArray<ClassInlinedFields>(100, mtServiceability);
1874   }
1875   _this->_inlined_field_map->append(ClassInlinedFields(klass, base_index));
1876 
1877   // counters for dumping classes with inlined fields
1878   _this->_classes_count++;
1879   _this->_inlined_fields_count += count;
1880 }
1881 
1882 void InlinedObjects::dump_inlined_field_names(AbstractDumpWriter* writer) {
1883   InlinedFieldNameDumper nameDumper(writer, this, inlined_field_names_callback);
1884   ClassLoaderDataGraph::classes_do(&nameDumper);
1885 
1886   if (_inlined_field_map != nullptr) {
1887     // prepare the map for  get_base_index_for().
1888     _inlined_field_map->sort(ClassInlinedFields::compare);
1889   }
1890 }
1891 
1892 uintx InlinedObjects::get_base_index_for(Klass* k) {
1893   if (_inlined_field_map != nullptr) {
1894     bool found = false;
1895     int idx = _inlined_field_map->find_sorted<ClassInlinedFields, ClassInlinedFields::compare>(ClassInlinedFields(k, 0), found);
1896     if (found) {
1897         return _inlined_field_map->at(idx).base_index;
1898     }
1899   }
1900 
1901   // return max_uintx, so get_next_string_id returns 0.
1902   return max_uintx;
1903 }
1904 
1905 uintx InlinedObjects::get_next_string_id(uintx id) {
1906   if (++id == _min_string_id) {
1907     return _max_string_id + 1;
1908   }
1909   return id;
1910 }
1911 
1912 void InlinedObjects::dump_classed_with_inlined_fields(AbstractDumpWriter* writer) {
1913   if (_classes_count != 0) {
1914     // Record for each class contains tag(u1), class ID and count(u2)
1915     // for each inlined field index(u2), synthetic fields count(u2), original field name and class ID
1916     int size = _classes_count * (1 + sizeof(address) + 2)
1917              + _inlined_fields_count * (2 + 2 + sizeof(address) + sizeof(address));
1918     DumperSupport::write_header(writer, HPROF_INLINED_FIELDS, (u4)size);
1919 
1920     InlinedFieldsDumper dumper(writer);
1921     ClassLoaderDataGraph::classes_do(&dumper);
1922   }
1923 }
1924 
1925 void InlinedObjects::add_flat_array(oop array) {
1926   if (_flat_arrays == nullptr) {
1927     _flat_arrays = new (mtServiceability) GrowableArray<oop>(100, mtServiceability);
1928   }
1929   _flat_arrays->append(array);
1930 }
1931 
1932 void InlinedObjects::dump_flat_arrays(AbstractDumpWriter* writer) {
1933   if (_flat_arrays != nullptr) {
1934     // For each flat array the record contains tag (u1), object ID and class ID.
1935     int size = _flat_arrays->length() * (1 + sizeof(address) + sizeof(address));
1936 
1937     DumperSupport::write_header(writer, HPROF_FLAT_ARRAYS, (u4)size);
1938     for (GrowableArrayIterator<oop> it = _flat_arrays->begin(); it != _flat_arrays->end(); ++it) {
1939       flatArrayOop array = flatArrayOop(*it);
1940       FlatArrayKlass* array_klass = FlatArrayKlass::cast(array->klass());
1941       InlineKlass* element_klass = array_klass->element_klass();
1942       writer->write_u1(HPROF_FLAT_ARRAY);
1943       writer->write_objectID(array);
1944       writer->write_classID(element_klass);
1945     }
1946   }
1947 }
1948 
1949 
1950 // Support class used to generate HPROF_UTF8 records from the entries in the
1951 // SymbolTable.
1952 
1953 class SymbolTableDumper : public SymbolClosure {
1954  private:
1955   AbstractDumpWriter* _writer;
1956   AbstractDumpWriter* writer() const                { return _writer; }
1957  public:
1958   SymbolTableDumper(AbstractDumpWriter* writer)     { _writer = writer; }
1959   void do_symbol(Symbol** p);
1960 };
1961 
1962 void SymbolTableDumper::do_symbol(Symbol** p) {
1963   ResourceMark rm;
1964   Symbol* sym = *p;
1965   int len = sym->utf8_length();
1966   if (len > 0) {
1967     char* s = sym->as_utf8();
1968     DumperSupport::write_header(writer(), HPROF_UTF8, oopSize + len);
1969     writer()->write_symbolID(sym);
1970     writer()->write_raw(s, len);
1971   }
1972 }
1973 
1974 // Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records
1975 
1976 class JNILocalsDumper : public OopClosure {
1977  private:
1978   AbstractDumpWriter* _writer;
1979   u4 _thread_serial_num;
1980   int _frame_num;
1981   AbstractDumpWriter* writer() const                { return _writer; }
1982  public:
1983   JNILocalsDumper(AbstractDumpWriter* writer, u4 thread_serial_num) {
1984     _writer = writer;
1985     _thread_serial_num = thread_serial_num;
1986     _frame_num = -1;  // default - empty stack
1987   }
1988   void set_frame_number(int n) { _frame_num = n; }
1989   void do_oop(oop* obj_p);
1990   void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
1991 };
1992 
1993 void JNILocalsDumper::do_oop(oop* obj_p) {
1994   // ignore null handles
1995   oop o = *obj_p;
1996   if (o != nullptr) {
1997     u4 size = 1 + sizeof(address) + 4 + 4;
1998     writer()->start_sub_record(HPROF_GC_ROOT_JNI_LOCAL, size);
1999     writer()->write_objectID(o);
2000     writer()->write_u4(_thread_serial_num);
2001     writer()->write_u4((u4)_frame_num);
2002     writer()->end_sub_record();
2003   }
2004 }
2005 
2006 
2007 // Support class used to generate HPROF_GC_ROOT_JNI_GLOBAL records
2008 
2009 class JNIGlobalsDumper : public OopClosure {
2010  private:
2011   AbstractDumpWriter* _writer;
2012   AbstractDumpWriter* writer() const                { return _writer; }
2013 
2014  public:
2015   JNIGlobalsDumper(AbstractDumpWriter* writer) {
2016     _writer = writer;
2017   }
2018   void do_oop(oop* obj_p);
2019   void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2020 };
2021 
2022 void JNIGlobalsDumper::do_oop(oop* obj_p) {
2023   oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2024 
2025   // ignore these
2026   if (o == nullptr) return;
2027   // we ignore global ref to symbols and other internal objects
2028   if (o->is_instance() || o->is_objArray() || o->is_typeArray()) {
2029     u4 size = 1 + 2 * sizeof(address);
2030     writer()->start_sub_record(HPROF_GC_ROOT_JNI_GLOBAL, size);
2031     writer()->write_objectID(o);
2032     writer()->write_rootID(obj_p);      // global ref ID
2033     writer()->end_sub_record();
2034   }
2035 };
2036 
2037 // Support class used to generate HPROF_GC_ROOT_STICKY_CLASS records
2038 
2039 class StickyClassDumper : public KlassClosure {
2040  private:
2041   AbstractDumpWriter* _writer;
2042   AbstractDumpWriter* writer() const                { return _writer; }
2043  public:
2044   StickyClassDumper(AbstractDumpWriter* writer) {
2045     _writer = writer;
2046   }
2047   void do_klass(Klass* k) {
2048     if (k->is_instance_klass()) {
2049       InstanceKlass* ik = InstanceKlass::cast(k);
2050       u4 size = 1 + sizeof(address);
2051       writer()->start_sub_record(HPROF_GC_ROOT_STICKY_CLASS, size);
2052       writer()->write_classID(ik);
2053       writer()->end_sub_record();
2054     }
2055   }
2056 };
2057 
2058 // Support class used to generate HPROF_GC_ROOT_JAVA_FRAME records.
2059 
2060 class JavaStackRefDumper : public StackObj {
2061 private:
2062   AbstractDumpWriter* _writer;
2063   u4 _thread_serial_num;
2064   int _frame_num;
2065   AbstractDumpWriter* writer() const { return _writer; }
2066 public:
2067   JavaStackRefDumper(AbstractDumpWriter* writer, u4 thread_serial_num)
2068       : _writer(writer), _thread_serial_num(thread_serial_num), _frame_num(-1) // default - empty stack
2069   {
2070   }
2071 
2072   void set_frame_number(int n) { _frame_num = n; }
2073 
2074   void dump_java_stack_refs(StackValueCollection* values);
2075 };
2076 
2077 void JavaStackRefDumper::dump_java_stack_refs(StackValueCollection* values) {
2078   for (int index = 0; index < values->size(); index++) {
2079     if (values->at(index)->type() == T_OBJECT) {
2080       oop o = values->obj_at(index)();
2081       if (o != nullptr) {
2082         u4 size = 1 + sizeof(address) + 4 + 4;
2083         writer()->start_sub_record(HPROF_GC_ROOT_JAVA_FRAME, size);
2084         writer()->write_objectID(o);
2085         writer()->write_u4(_thread_serial_num);
2086         writer()->write_u4((u4)_frame_num);
2087         writer()->end_sub_record();
2088       }
2089     }
2090   }
2091 }
2092 
2093 // Class to collect, store and dump thread-related data:
2094 // - HPROF_TRACE and HPROF_FRAME records;
2095 // - HPROF_GC_ROOT_THREAD_OBJ/HPROF_GC_ROOT_JAVA_FRAME/HPROF_GC_ROOT_JNI_LOCAL subrecords.
2096 class ThreadDumper : public CHeapObj<mtInternal> {
2097 public:
2098   enum class ThreadType { Platform, MountedVirtual, UnmountedVirtual };
2099 
2100 private:
2101   ThreadType _thread_type;
2102   JavaThread* _java_thread;
2103   oop _thread_oop;
2104 
2105   GrowableArray<StackFrameInfo*>* _frames;
2106   // non-null if the thread is OOM thread
2107   Method* _oome_constructor;
2108   int _thread_serial_num;
2109   int _start_frame_serial_num;
2110 
2111   vframe* get_top_frame() const;
2112 
2113 public:
2114   static bool should_dump_pthread(JavaThread* thread) {
2115     return thread->threadObj() != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view();
2116   }
2117 
2118   static bool should_dump_vthread(oop vt) {
2119     return java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::NEW
2120         && java_lang_VirtualThread::state(vt) != java_lang_VirtualThread::TERMINATED;
2121   }
2122 
2123   ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop);
2124 
2125   // affects frame_count
2126   void add_oom_frame(Method* oome_constructor) {
2127     assert(_start_frame_serial_num == 0, "add_oom_frame cannot be called after init_serial_nums");
2128     _oome_constructor = oome_constructor;
2129   }
2130 
2131   void init_serial_nums(volatile int* thread_counter, volatile int* frame_counter) {
2132     assert(_start_frame_serial_num == 0, "already initialized");
2133     _thread_serial_num = Atomic::fetch_then_add(thread_counter, 1);
2134     _start_frame_serial_num = Atomic::fetch_then_add(frame_counter, frame_count());
2135   }
2136 
2137   bool oom_thread() const {
2138     return _oome_constructor != nullptr;
2139   }
2140 
2141   int frame_count() const {
2142     return _frames->length() + (oom_thread() ? 1 : 0);
2143   }
2144 
2145   u4 thread_serial_num() const {
2146     return (u4)_thread_serial_num;
2147   }
2148 
2149   u4 stack_trace_serial_num() const {
2150     return (u4)(_thread_serial_num + STACK_TRACE_ID);
2151   }
2152 
2153   // writes HPROF_TRACE and HPROF_FRAME records
2154   // returns number of dumped frames
2155   void dump_stack_traces(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map);
2156 
2157   // writes HPROF_GC_ROOT_THREAD_OBJ subrecord
2158   void dump_thread_obj(AbstractDumpWriter* writer);
2159 
2160   // Walk the stack of the thread.
2161   // Dumps a HPROF_GC_ROOT_JAVA_FRAME subrecord for each local
2162   // Dumps a HPROF_GC_ROOT_JNI_LOCAL subrecord for each JNI local
2163   void dump_stack_refs(AbstractDumpWriter* writer);
2164 
2165 };
2166 
2167 ThreadDumper::ThreadDumper(ThreadType thread_type, JavaThread* java_thread, oop thread_oop)
2168     : _thread_type(thread_type), _java_thread(java_thread), _thread_oop(thread_oop),
2169       _oome_constructor(nullptr),
2170       _thread_serial_num(0), _start_frame_serial_num(0)
2171 {
2172   // sanity checks
2173   if (_thread_type == ThreadType::UnmountedVirtual) {
2174     assert(_java_thread == nullptr, "sanity");
2175     assert(_thread_oop != nullptr, "sanity");
2176   } else {
2177     assert(_java_thread != nullptr, "sanity");
2178     assert(_thread_oop != nullptr, "sanity");
2179   }
2180 
2181   _frames = new (mtServiceability) GrowableArray<StackFrameInfo*>(10, mtServiceability);
2182   bool stop_at_vthread_entry = _thread_type == ThreadType::MountedVirtual;
2183 
2184   // vframes are resource allocated
2185   Thread* current_thread = Thread::current();
2186   ResourceMark rm(current_thread);
2187   HandleMark hm(current_thread);
2188 
2189   for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) {
2190     if (stop_at_vthread_entry && vf->is_vthread_entry()) {
2191       break;
2192     }
2193     if (vf->is_java_frame()) {
2194       javaVFrame* jvf = javaVFrame::cast(vf);
2195       _frames->append(new StackFrameInfo(jvf, false));
2196     } else {
2197       // ignore non-Java frames
2198     }
2199   }
2200 }
2201 
2202 void ThreadDumper::dump_stack_traces(AbstractDumpWriter* writer, GrowableArray<Klass*>* klass_map) {
2203   assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_nums are not initialized");
2204 
2205   // write HPROF_FRAME records for this thread's stack trace
2206   int depth = _frames->length();
2207   int frame_serial_num = _start_frame_serial_num;
2208 
2209   if (oom_thread()) {
2210     // OOM thread
2211     // write fake frame that makes it look like the thread, which caused OOME,
2212     // is in the OutOfMemoryError zero-parameter constructor
2213     int oome_serial_num = klass_map->find(_oome_constructor->method_holder());
2214     // the class serial number starts from 1
2215     assert(oome_serial_num > 0, "OutOfMemoryError class not found");
2216     DumperSupport::dump_stack_frame(writer, ++frame_serial_num, oome_serial_num, _oome_constructor, 0);
2217     depth++;
2218   }
2219 
2220   for (int j = 0; j < _frames->length(); j++) {
2221     StackFrameInfo* frame = _frames->at(j);
2222     Method* m = frame->method();
2223     int class_serial_num = klass_map->find(m->method_holder());
2224     // the class serial number starts from 1
2225     assert(class_serial_num > 0, "class not found");
2226     DumperSupport::dump_stack_frame(writer, ++frame_serial_num, class_serial_num, m, frame->bci());
2227   }
2228 
2229   // write HPROF_TRACE record for the thread
2230   DumperSupport::write_header(writer, HPROF_TRACE, checked_cast<u4>(3 * sizeof(u4) + depth * oopSize));
2231   writer->write_u4(stack_trace_serial_num());   // stack trace serial number
2232   writer->write_u4(thread_serial_num());        // thread serial number
2233   writer->write_u4((u4)depth);                  // frame count (including oom frame)
2234   for (int j = 1; j <= depth; j++) {
2235     writer->write_id(_start_frame_serial_num + j);
2236   }
2237 }
2238 
2239 void ThreadDumper::dump_thread_obj(AbstractDumpWriter * writer) {
2240   assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized");
2241 
2242   u4 size = 1 + sizeof(address) + 4 + 4;
2243   writer->start_sub_record(HPROF_GC_ROOT_THREAD_OBJ, size);
2244   writer->write_objectID(_thread_oop);
2245   writer->write_u4(thread_serial_num());      // thread serial number
2246   writer->write_u4(stack_trace_serial_num()); // stack trace serial number
2247   writer->end_sub_record();
2248 }
2249 
2250 void ThreadDumper::dump_stack_refs(AbstractDumpWriter * writer) {
2251   assert(_thread_serial_num != 0 && _start_frame_serial_num != 0, "serial_num is not initialized");
2252 
2253   JNILocalsDumper blk(writer, thread_serial_num());
2254   if (_thread_type == ThreadType::Platform) {
2255     if (!_java_thread->has_last_Java_frame()) {
2256       // no last java frame but there may be JNI locals
2257       _java_thread->active_handles()->oops_do(&blk);
2258       return;
2259     }
2260   }
2261 
2262   JavaStackRefDumper java_ref_dumper(writer, thread_serial_num());
2263 
2264   // vframes are resource allocated
2265   Thread* current_thread = Thread::current();
2266   ResourceMark rm(current_thread);
2267   HandleMark hm(current_thread);
2268 
2269   bool stopAtVthreadEntry = _thread_type == ThreadType::MountedVirtual;
2270   frame* last_entry_frame = nullptr;
2271   bool is_top_frame = true;
2272   int depth = 0;
2273   if (oom_thread()) {
2274     depth++;
2275   }
2276 
2277   for (vframe* vf = get_top_frame(); vf != nullptr; vf = vf->sender()) {
2278     if (stopAtVthreadEntry && vf->is_vthread_entry()) {
2279       break;
2280     }
2281 
2282     if (vf->is_java_frame()) {
2283       javaVFrame* jvf = javaVFrame::cast(vf);
2284       if (!(jvf->method()->is_native())) {
2285         java_ref_dumper.set_frame_number(depth);
2286         java_ref_dumper.dump_java_stack_refs(jvf->locals());
2287         java_ref_dumper.dump_java_stack_refs(jvf->expressions());
2288       } else {
2289         // native frame
2290         blk.set_frame_number(depth);
2291         if (is_top_frame) {
2292           // JNI locals for the top frame.
2293           assert(_java_thread != nullptr, "impossible for unmounted vthread");
2294           _java_thread->active_handles()->oops_do(&blk);
2295         } else {
2296           if (last_entry_frame != nullptr) {
2297             // JNI locals for the entry frame
2298             assert(last_entry_frame->is_entry_frame(), "checking");
2299             last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(&blk);
2300           }
2301         }
2302       }
2303       last_entry_frame = nullptr;
2304       // increment only for Java frames
2305       depth++;
2306     } else {
2307       // externalVFrame - for an entry frame then we report the JNI locals
2308       // when we find the corresponding javaVFrame
2309       frame* fr = vf->frame_pointer();
2310       assert(fr != nullptr, "sanity check");
2311       if (fr->is_entry_frame()) {
2312         last_entry_frame = fr;
2313       }
2314     }
2315   is_top_frame = false;
2316   }
2317   assert(depth == frame_count(), "total number of Java frames not matched");
2318 }
2319 
2320 vframe* ThreadDumper::get_top_frame() const {
2321   if (_thread_type == ThreadType::UnmountedVirtual) {
2322     ContinuationWrapper cont(java_lang_VirtualThread::continuation(_thread_oop));
2323     if (cont.is_empty()) {
2324       return nullptr;
2325     }
2326     assert(!cont.is_mounted(), "sanity check");
2327     stackChunkOop chunk = cont.last_nonempty_chunk();
2328     if (chunk == nullptr || chunk->is_empty()) {
2329       return nullptr;
2330     }
2331 
2332     RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include);
2333     frame fr = chunk->top_frame(&reg_map);
2334     vframe* vf = vframe::new_vframe(&fr, &reg_map, nullptr); // don't need JavaThread
2335     return vf;
2336   }
2337 
2338   RegisterMap reg_map(_java_thread,
2339       RegisterMap::UpdateMap::include,
2340       RegisterMap::ProcessFrames::include,
2341       RegisterMap::WalkContinuation::skip);
2342   switch (_thread_type) {
2343   case ThreadType::Platform:
2344     if (!_java_thread->has_last_Java_frame()) {
2345       return nullptr;
2346     }
2347     return _java_thread->is_vthread_mounted()
2348         ? _java_thread->carrier_last_java_vframe(&reg_map)
2349         : _java_thread->platform_thread_last_java_vframe(&reg_map);
2350 
2351   case ThreadType::MountedVirtual:
2352     return _java_thread->last_java_vframe(&reg_map);
2353 
2354   default: // make compilers happy
2355       break;
2356   }
2357   ShouldNotReachHere();
2358   return nullptr;
2359 }
2360 
2361 
2362 class VM_HeapDumper;
2363 
2364 // Support class using when iterating over the heap.
2365 class HeapObjectDumper : public ObjectClosure {
2366  private:
2367   AbstractDumpWriter* _writer;
2368   AbstractDumpWriter* writer()                  { return _writer; }
2369 
2370   DumperClassCacheTable _class_cache;
2371 
2372  public:
2373   HeapObjectDumper(AbstractDumpWriter* writer) {
2374     _writer = writer;
2375   }
2376 
2377   // called for each object in the heap
2378   void do_object(oop o);
2379 };
2380 
2381 void HeapObjectDumper::do_object(oop o) {
2382   // skip classes as these emitted as HPROF_GC_CLASS_DUMP records
2383   if (o->klass() == vmClasses::Class_klass()) {
2384     if (!java_lang_Class::is_primitive(o)) {
2385       return;
2386     }
2387   }
2388 
2389   if (DumperSupport::mask_dormant_archived_object(o) == nullptr) {
2390     log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o), o->klass()->external_name());
2391     return;
2392   }
2393 
2394   if (o->is_instance()) {
2395     // create a HPROF_GC_INSTANCE record for each object
2396     DumperSupport::dump_instance(writer(), o, &_class_cache);
2397   } else if (o->is_objArray()) {
2398     // create a HPROF_GC_OBJ_ARRAY_DUMP record for each object array
2399     DumperSupport::dump_object_array(writer(), objArrayOop(o));
2400   } else if (o->is_flatArray()) {
2401     DumperSupport::dump_flat_array(writer(), flatArrayOop(o), &_class_cache);
2402   } else if (o->is_typeArray()) {
2403     // create a HPROF_GC_PRIM_ARRAY_DUMP record for each type array
2404     DumperSupport::dump_prim_array(writer(), typeArrayOop(o));
2405   }
2406 }
2407 
2408 // The dumper controller for parallel heap dump
2409 class DumperController : public CHeapObj<mtInternal> {
2410  private:
2411    Monitor* _lock;
2412    const uint   _dumper_number;
2413    uint   _complete_number;
2414 
2415  public:
2416    DumperController(uint number) :
2417      _lock(new (std::nothrow) PaddedMonitor(Mutex::safepoint, "DumperController_lock")),
2418      _dumper_number(number),
2419      _complete_number(0) { }
2420 
2421    ~DumperController() { delete _lock; }
2422 
2423    void dumper_complete(DumpWriter* local_writer, DumpWriter* global_writer) {
2424      MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
2425      _complete_number++;
2426      // propagate local error to global if any
2427      if (local_writer->has_error()) {
2428        global_writer->set_error(local_writer->error());
2429      }
2430      ml.notify();
2431    }
2432 
2433    void wait_all_dumpers_complete() {
2434      MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
2435      while (_complete_number != _dumper_number) {
2436         ml.wait();
2437      }
2438    }
2439 };
2440 
2441 // DumpMerger merges separate dump files into a complete one
2442 class DumpMerger : public StackObj {
2443 private:
2444   DumpWriter* _writer;
2445   InlinedObjects*  _inlined_objects;
2446   const char* _path;
2447   bool _has_error;
2448   int _dump_seq;
2449 
2450 private:
2451   void merge_file(char* path);
2452   void merge_done();
2453   void set_error(const char* msg);
2454 
2455 public:
2456   DumpMerger(const char* path, DumpWriter* writer, InlinedObjects* inlined_objects, int dump_seq) :
2457     _writer(writer),
2458     _inlined_objects(inlined_objects),
2459     _path(path),
2460     _has_error(_writer->has_error()),
2461     _dump_seq(dump_seq) {}
2462 
2463   void do_merge();
2464 };
2465 
2466 void DumpMerger::merge_done() {
2467   // Writes the HPROF_HEAP_DUMP_END record.
2468   if (!_has_error) {
2469     DumperSupport::end_of_dump(_writer);
2470     _inlined_objects->dump_flat_arrays(_writer);
2471     _writer->flush();
2472     _inlined_objects->release();
2473   }
2474   _dump_seq = 0; //reset
2475 }
2476 
2477 void DumpMerger::set_error(const char* msg) {
2478   assert(msg != nullptr, "sanity check");
2479   log_error(heapdump)("%s (file: %s)", msg, _path);
2480   _writer->set_error(msg);
2481   _has_error = true;
2482 }
2483 
2484 #ifdef LINUX
2485 // Merge segmented heap files via sendfile, it's more efficient than the
2486 // read+write combination, which would require transferring data to and from
2487 // user space.
2488 void DumpMerger::merge_file(char* path) {
2489   assert(!SafepointSynchronize::is_at_safepoint(), "merging happens outside safepoint");
2490   TraceTime timer("Merge segmented heap file directly", TRACETIME_LOG(Info, heapdump));
2491 
2492   int segment_fd = os::open(path, O_RDONLY, 0);
2493   if (segment_fd == -1) {
2494     set_error("Can not open segmented heap file during merging");
2495     return;
2496   }
2497 
2498   struct stat st;
2499   if (os::stat(path, &st) != 0) {
2500     ::close(segment_fd);
2501     set_error("Can not get segmented heap file size during merging");
2502     return;
2503   }
2504 
2505   // A successful call to sendfile may write fewer bytes than requested; the
2506   // caller should be prepared to retry the call if there were unsent bytes.
2507   jlong offset = 0;
2508   while (offset < st.st_size) {
2509     int ret = os::Linux::sendfile(_writer->get_fd(), segment_fd, &offset, st.st_size);
2510     if (ret == -1) {
2511       ::close(segment_fd);
2512       set_error("Failed to merge segmented heap file");
2513       return;
2514     }
2515   }
2516 
2517   // As sendfile variant does not call the write method of the global writer,
2518   // bytes_written is also incorrect for this variant, we need to explicitly
2519   // accumulate bytes_written for the global writer in this case
2520   julong accum = _writer->bytes_written() + st.st_size;
2521   _writer->set_bytes_written(accum);
2522   ::close(segment_fd);
2523 }
2524 #else
2525 // Generic implementation using read+write
2526 void DumpMerger::merge_file(char* path) {
2527   assert(!SafepointSynchronize::is_at_safepoint(), "merging happens outside safepoint");
2528   TraceTime timer("Merge segmented heap file", TRACETIME_LOG(Info, heapdump));
2529 
2530   fileStream segment_fs(path, "rb");
2531   if (!segment_fs.is_open()) {
2532     set_error("Can not open segmented heap file during merging");
2533     return;
2534   }
2535 
2536   jlong total = 0;
2537   size_t cnt = 0;
2538   char read_buf[4096];
2539   while ((cnt = segment_fs.read(read_buf, 1, 4096)) != 0) {
2540     _writer->write_raw(read_buf, cnt);
2541     total += cnt;
2542   }
2543 
2544   _writer->flush();
2545   if (segment_fs.fileSize() != total) {
2546     set_error("Merged heap dump is incomplete");
2547   }
2548 }
2549 #endif
2550 
2551 void DumpMerger::do_merge() {
2552   assert(!SafepointSynchronize::is_at_safepoint(), "merging happens outside safepoint");
2553   TraceTime timer("Merge heap files complete", TRACETIME_LOG(Info, heapdump));
2554 
2555   // Since contents in segmented heap file were already zipped, we don't need to zip
2556   // them again during merging.
2557   AbstractCompressor* saved_compressor = _writer->compressor();
2558   _writer->set_compressor(nullptr);
2559 
2560   // Merge the content of the remaining files into base file. Regardless of whether
2561   // the merge process is successful or not, these segmented files will be deleted.
2562   char path[JVM_MAXPATHLEN];
2563   for (int i = 0; i < _dump_seq; i++) {
2564     memset(path, 0, JVM_MAXPATHLEN);
2565     os::snprintf(path, JVM_MAXPATHLEN, "%s.p%d", _path, i);
2566     if (!_has_error) {
2567       merge_file(path);
2568     }
2569     // Delete selected segmented heap file nevertheless
2570     if (remove(path) != 0) {
2571       log_info(heapdump)("Removal of segment file (%d) failed (%d)", i, errno);
2572     }
2573   }
2574 
2575   // restore compressor for further use
2576   _writer->set_compressor(saved_compressor);
2577   merge_done();
2578 }
2579 
2580 // The VM operation wraps DumpMerger so that it could be performed by VM thread
2581 class VM_HeapDumpMerge : public VM_Operation {
2582 private:
2583   DumpMerger* _merger;
2584 public:
2585   VM_HeapDumpMerge(DumpMerger* merger) : _merger(merger) {}
2586   VMOp_Type type() const { return VMOp_HeapDumpMerge; }
2587   // heap dump merge could happen outside safepoint
2588   virtual bool evaluate_at_safepoint() const { return false; }
2589   void doit() {
2590     _merger->do_merge();
2591   }
2592 };
2593 
2594 // The VM operation that performs the heap dump
2595 class VM_HeapDumper : public VM_GC_Operation, public WorkerTask {
2596  private:
2597   static VM_HeapDumper*   _global_dumper;
2598   static DumpWriter*      _global_writer;
2599   DumpWriter*             _local_writer;
2600   JavaThread*             _oome_thread;
2601   Method*                 _oome_constructor;
2602   bool                    _gc_before_heap_dump;
2603   GrowableArray<Klass*>*  _klass_map;
2604 
2605   ThreadDumper**          _thread_dumpers; // platform, carrier and mounted virtual threads
2606   int                     _thread_dumpers_count;
2607   volatile int            _thread_serial_num;
2608   volatile int            _frame_serial_num;
2609 
2610   volatile int            _dump_seq;
2611 
2612   // Inlined object support.
2613   InlinedObjects          _inlined_objects;
2614 
2615   // parallel heap dump support
2616   uint                    _num_dumper_threads;
2617   DumperController*       _dumper_controller;
2618   ParallelObjectIterator* _poi;
2619   // worker id of VMDumper thread.
2620   static const size_t VMDumperWorkerId = 0;
2621   // VM dumper dumps both heap and non-heap data, other dumpers dump heap-only data.
2622   static bool is_vm_dumper(uint worker_id) { return worker_id == VMDumperWorkerId; }
2623 
2624   // accessors and setters
2625   static VM_HeapDumper* dumper()         {  assert(_global_dumper != nullptr, "Error"); return _global_dumper; }
2626   static DumpWriter* writer()            {  assert(_global_writer != nullptr, "Error"); return _global_writer; }
2627 
2628   void set_global_dumper() {
2629     assert(_global_dumper == nullptr, "Error");
2630     _global_dumper = this;
2631   }
2632   void set_global_writer() {
2633     assert(_global_writer == nullptr, "Error");
2634     _global_writer = _local_writer;
2635   }
2636   void clear_global_dumper() { _global_dumper = nullptr; }
2637   void clear_global_writer() { _global_writer = nullptr; }
2638 
2639   bool skip_operation() const;
2640 
2641   // create dump writer for every parallel dump thread
2642   DumpWriter* create_local_writer();
2643 
2644   // writes a HPROF_LOAD_CLASS record
2645   static void do_load_class(Klass* k);
2646 
2647   // writes a HPROF_GC_CLASS_DUMP record for the given class
2648   static void do_class_dump(Klass* k);
2649 
2650   // HPROF_GC_ROOT_THREAD_OBJ records for platform and mounted virtual threads
2651   void dump_threads();
2652 
2653   void add_class_serial_number(Klass* k, int serial_num) {
2654     _klass_map->at_put_grow(serial_num, k);
2655   }
2656 
2657   bool is_oom_thread(JavaThread* thread) const {
2658     return thread == _oome_thread && _oome_constructor != nullptr;
2659   }
2660 
2661   // HPROF_TRACE and HPROF_FRAME records for platform and mounted virtual threads
2662   void dump_stack_traces();
2663 
2664  public:
2665   VM_HeapDumper(DumpWriter* writer, bool gc_before_heap_dump, bool oome, uint num_dump_threads) :
2666     VM_GC_Operation(0 /* total collections,      dummy, ignored */,
2667                     GCCause::_heap_dump /* GC Cause */,
2668                     0 /* total full collections, dummy, ignored */,
2669                     gc_before_heap_dump),
2670     WorkerTask("dump heap") {
2671     _local_writer = writer;
2672     _gc_before_heap_dump = gc_before_heap_dump;
2673     _klass_map = new (mtServiceability) GrowableArray<Klass*>(INITIAL_CLASS_COUNT, mtServiceability);
2674 
2675     _thread_dumpers = nullptr;
2676     _thread_dumpers_count = 0;
2677     _thread_serial_num = 1;
2678     _frame_serial_num = 1;
2679 
2680     _dump_seq = 0;
2681     _num_dumper_threads = num_dump_threads;
2682     _dumper_controller = nullptr;
2683     _poi = nullptr;
2684     if (oome) {
2685       assert(!Thread::current()->is_VM_thread(), "Dump from OutOfMemoryError cannot be called by the VMThread");
2686       // get OutOfMemoryError zero-parameter constructor
2687       InstanceKlass* oome_ik = vmClasses::OutOfMemoryError_klass();
2688       _oome_constructor = oome_ik->find_method(vmSymbols::object_initializer_name(),
2689                                                           vmSymbols::void_method_signature());
2690       // get thread throwing OOME when generating the heap dump at OOME
2691       _oome_thread = JavaThread::current();
2692     } else {
2693       _oome_thread = nullptr;
2694       _oome_constructor = nullptr;
2695     }
2696   }
2697 
2698   ~VM_HeapDumper() {
2699     if (_thread_dumpers != nullptr) {
2700       for (int i = 0; i < _thread_dumpers_count; i++) {
2701         delete _thread_dumpers[i];
2702       }
2703       FREE_C_HEAP_ARRAY(ThreadDumper*, _thread_dumpers);
2704     }
2705 
2706     if (_dumper_controller != nullptr) {
2707       delete _dumper_controller;
2708       _dumper_controller = nullptr;
2709     }
2710     delete _klass_map;
2711   }
2712   int dump_seq()           { return _dump_seq; }
2713   bool is_parallel_dump()  { return _num_dumper_threads > 1; }
2714   bool can_parallel_dump(WorkerThreads* workers);
2715 
2716   InlinedObjects* inlined_objects() { return &_inlined_objects; }
2717 
2718   VMOp_Type type() const { return VMOp_HeapDumper; }
2719   virtual bool doit_prologue();
2720   void doit();
2721   void work(uint worker_id);
2722 };
2723 
2724 VM_HeapDumper* VM_HeapDumper::_global_dumper = nullptr;
2725 DumpWriter*    VM_HeapDumper::_global_writer = nullptr;
2726 
2727 bool VM_HeapDumper::skip_operation() const {
2728   return false;
2729 }
2730 
2731 // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
2732 void DumperSupport::end_of_dump(AbstractDumpWriter* writer) {
2733   writer->finish_dump_segment();
2734 
2735   writer->write_u1(HPROF_HEAP_DUMP_END);
2736   writer->write_u4(0);
2737   writer->write_u4(0);
2738 }
2739 
2740 // writes a HPROF_LOAD_CLASS record for the class
2741 void VM_HeapDumper::do_load_class(Klass* k) {
2742   static u4 class_serial_num = 0;
2743 
2744   // len of HPROF_LOAD_CLASS record
2745   u4 remaining = 2*oopSize + 2*sizeof(u4);
2746 
2747   DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);
2748 
2749   // class serial number is just a number
2750   writer()->write_u4(++class_serial_num);
2751 
2752   // class ID
2753   writer()->write_classID(k);
2754 
2755   // add the Klass* and class serial number pair
2756   dumper()->add_class_serial_number(k, class_serial_num);
2757 
2758   writer()->write_u4(STACK_TRACE_ID);
2759 
2760   // class name ID
2761   Symbol* name = k->name();
2762   writer()->write_symbolID(name);
2763 }
2764 
2765 // writes a HPROF_GC_CLASS_DUMP record for the given class
2766 void VM_HeapDumper::do_class_dump(Klass* k) {
2767   if (k->is_instance_klass()) {
2768     DumperSupport::dump_instance_class(writer(), k);
2769   } else {
2770     DumperSupport::dump_array_class(writer(), k);
2771   }
2772 }
2773 
2774 // Write a HPROF_GC_ROOT_THREAD_OBJ record for platform/carrier and mounted virtual threads.
2775 // Then walk the stack so that locals and JNI locals are dumped.
2776 void VM_HeapDumper::dump_threads() {
2777     for (int i = 0; i < _thread_dumpers_count; i++) {
2778         _thread_dumpers[i]->dump_thread_obj(writer());
2779         _thread_dumpers[i]->dump_stack_refs(writer());
2780     }
2781 }
2782 
2783 bool VM_HeapDumper::doit_prologue() {
2784   if (_gc_before_heap_dump && UseZGC) {
2785     // ZGC cannot perform a synchronous GC cycle from within the VM thread.
2786     // So ZCollectedHeap::collect_as_vm_thread() is a noop. To respect the
2787     // _gc_before_heap_dump flag a synchronous GC cycle is performed from
2788     // the caller thread in the prologue.
2789     Universe::heap()->collect(GCCause::_heap_dump);
2790   }
2791   return VM_GC_Operation::doit_prologue();
2792 }
2793 
2794 bool VM_HeapDumper::can_parallel_dump(WorkerThreads* workers) {
2795   bool can_parallel = true;
2796   uint num_active_workers = workers != nullptr ? workers->active_workers() : 0;
2797   uint num_requested_dump_threads = _num_dumper_threads;
2798   // check if we can dump in parallel based on requested and active threads
2799   if (num_active_workers <= 1 || num_requested_dump_threads <= 1) {
2800     _num_dumper_threads = 1;
2801     can_parallel = false;
2802   } else {
2803     // check if we have extra path room to accommodate segmented heap files
2804     const char* base_path = writer()->get_file_path();
2805     assert(base_path != nullptr, "sanity check");
2806     if ((strlen(base_path) + 7/*.p\d\d\d\d\0*/) >= JVM_MAXPATHLEN) {
2807       _num_dumper_threads = 1;
2808       can_parallel = false;
2809     } else {
2810       _num_dumper_threads = clamp(num_requested_dump_threads, 2U, num_active_workers);
2811     }
2812   }
2813 
2814   log_info(heapdump)("Requested dump threads %u, active dump threads %u, "
2815                      "actual dump threads %u, parallelism %s",
2816                      num_requested_dump_threads, num_active_workers,
2817                      _num_dumper_threads, can_parallel ? "true" : "false");
2818   return can_parallel;
2819 }
2820 
2821 // The VM operation that dumps the heap. The dump consists of the following
2822 // records:
2823 //
2824 //  HPROF_HEADER
2825 //  [HPROF_UTF8]*
2826 //  [HPROF_LOAD_CLASS]*
2827 //  [[HPROF_FRAME]*|HPROF_TRACE]*
2828 //  [HPROF_GC_CLASS_DUMP]*
2829 //  [HPROF_HEAP_DUMP_SEGMENT]*
2830 //  HPROF_HEAP_DUMP_END
2831 //
2832 // The HPROF_TRACE records represent the stack traces where the heap dump
2833 // is generated and a "dummy trace" record which does not include
2834 // any frames. The dummy trace record is used to be referenced as the
2835 // unknown object alloc site.
2836 //
2837 // Each HPROF_HEAP_DUMP_SEGMENT record has a length followed by sub-records.
2838 // To allow the heap dump be generated in a single pass we remember the position
2839 // of the dump length and fix it up after all sub-records have been written.
2840 // To generate the sub-records we iterate over the heap, writing
2841 // HPROF_GC_INSTANCE_DUMP, HPROF_GC_OBJ_ARRAY_DUMP, and HPROF_GC_PRIM_ARRAY_DUMP
2842 // records as we go. Once that is done we write records for some of the GC
2843 // roots.
2844 
2845 void VM_HeapDumper::doit() {
2846 
2847   CollectedHeap* ch = Universe::heap();
2848 
2849   ch->ensure_parsability(false); // must happen, even if collection does
2850                                  // not happen (e.g. due to GCLocker)
2851 
2852   if (_gc_before_heap_dump) {
2853     if (GCLocker::is_active()) {
2854       warning("GC locker is held; pre-heapdump GC was skipped");
2855     } else {
2856       ch->collect_as_vm_thread(GCCause::_heap_dump);
2857     }
2858   }
2859 
2860   // At this point we should be the only dumper active, so
2861   // the following should be safe.
2862   set_global_dumper();
2863   set_global_writer();
2864 
2865   WorkerThreads* workers = ch->safepoint_workers();
2866   if (!can_parallel_dump(workers)) {
2867     work(VMDumperWorkerId);
2868   } else {
2869     uint heap_only_dumper_threads = _num_dumper_threads - 1 /* VMDumper thread */;
2870     _dumper_controller = new (std::nothrow) DumperController(heap_only_dumper_threads);
2871     ParallelObjectIterator poi(_num_dumper_threads);
2872     _poi = &poi;
2873     workers->run_task(this, _num_dumper_threads);
2874     _poi = nullptr;
2875   }
2876 
2877   // Now we clear the global variables, so that a future dumper can run.
2878   clear_global_dumper();
2879   clear_global_writer();
2880 }
2881 
2882 // prepare DumpWriter for every parallel dump thread
2883 DumpWriter* VM_HeapDumper::create_local_writer() {
2884   char* path = NEW_RESOURCE_ARRAY(char, JVM_MAXPATHLEN);
2885   memset(path, 0, JVM_MAXPATHLEN);
2886 
2887   // generate segmented heap file path
2888   const char* base_path = writer()->get_file_path();
2889   // share global compressor, local DumpWriter is not responsible for its life cycle
2890   AbstractCompressor* compressor = writer()->compressor();
2891   int seq = Atomic::fetch_then_add(&_dump_seq, 1);
2892   os::snprintf(path, JVM_MAXPATHLEN, "%s.p%d", base_path, seq);
2893 
2894   // create corresponding writer for that
2895   DumpWriter* local_writer = new DumpWriter(path, writer()->is_overwrite(), compressor);
2896   return local_writer;
2897 }
2898 
2899 void VM_HeapDumper::work(uint worker_id) {
2900   // VM Dumper works on all non-heap data dumping and part of heap iteration.
2901   if (is_vm_dumper(worker_id)) {
2902     TraceTime timer("Dump non-objects", TRACETIME_LOG(Info, heapdump));
2903     // Write the file header - we always use 1.0.2
2904     const char* header = "JAVA PROFILE 1.0.2";
2905 
2906     // header is few bytes long - no chance to overflow int
2907     writer()->write_raw(header, strlen(header) + 1); // NUL terminated
2908     writer()->write_u4(oopSize);
2909     // timestamp is current time in ms
2910     writer()->write_u8(os::javaTimeMillis());
2911     // HPROF_UTF8 records
2912     SymbolTableDumper sym_dumper(writer());
2913     SymbolTable::symbols_do(&sym_dumper);
2914 
2915     // HPROF_UTF8 records for inlined field names.
2916     inlined_objects()->init();
2917     inlined_objects()->dump_inlined_field_names(writer());
2918 
2919     // HPROF_INLINED_FIELDS
2920     inlined_objects()->dump_classed_with_inlined_fields(writer());
2921 
2922     // write HPROF_LOAD_CLASS records
2923     {
2924       LockedClassesDo locked_load_classes(&do_load_class);
2925       ClassLoaderDataGraph::classes_do(&locked_load_classes);
2926     }
2927 
2928     // write HPROF_FRAME and HPROF_TRACE records
2929     // this must be called after _klass_map is built when iterating the classes above.
2930     dump_stack_traces();
2931 
2932     // HPROF_HEAP_DUMP/HPROF_HEAP_DUMP_SEGMENT starts here
2933 
2934     // Writes HPROF_GC_CLASS_DUMP records
2935     {
2936       LockedClassesDo locked_dump_class(&do_class_dump);
2937       ClassLoaderDataGraph::classes_do(&locked_dump_class);
2938     }
2939 
2940     // HPROF_GC_ROOT_THREAD_OBJ + frames + jni locals
2941     dump_threads();
2942 
2943     // HPROF_GC_ROOT_JNI_GLOBAL
2944     JNIGlobalsDumper jni_dumper(writer());
2945     JNIHandles::oops_do(&jni_dumper);
2946     // technically not jni roots, but global roots
2947     // for things like preallocated throwable backtraces
2948     Universe::vm_global()->oops_do(&jni_dumper);
2949     // HPROF_GC_ROOT_STICKY_CLASS
2950     // These should be classes in the null class loader data, and not all classes
2951     // if !ClassUnloading
2952     StickyClassDumper class_dumper(writer());
2953     ClassLoaderData::the_null_class_loader_data()->classes_do(&class_dumper);
2954   }
2955 
2956   // Heap iteration.
2957   // writes HPROF_GC_INSTANCE_DUMP records.
2958   // After each sub-record is written check_segment_length will be invoked
2959   // to check if the current segment exceeds a threshold. If so, a new
2960   // segment is started.
2961   // The HPROF_GC_CLASS_DUMP and HPROF_GC_INSTANCE_DUMP are the vast bulk
2962   // of the heap dump.
2963   if (!is_parallel_dump()) {
2964     assert(is_vm_dumper(worker_id), "must be");
2965     // == Serial dump
2966     ResourceMark rm;
2967     TraceTime timer("Dump heap objects", TRACETIME_LOG(Info, heapdump));
2968     HeapObjectDumper obj_dumper(writer());
2969     Universe::heap()->object_iterate(&obj_dumper);
2970     writer()->finish_dump_segment();
2971     // Writes the HPROF_HEAP_DUMP_END record because merge does not happen in serial dump
2972     DumperSupport::end_of_dump(writer());
2973     inlined_objects()->dump_flat_arrays(writer());
2974     writer()->flush();
2975     inlined_objects()->release();
2976   } else {
2977     // == Parallel dump
2978     ResourceMark rm;
2979     TraceTime timer("Dump heap objects in parallel", TRACETIME_LOG(Info, heapdump));
2980     DumpWriter* local_writer = is_vm_dumper(worker_id) ? writer() : create_local_writer();
2981     if (!local_writer->has_error()) {
2982       HeapObjectDumper obj_dumper(local_writer);
2983       _poi->object_iterate(&obj_dumper, worker_id);
2984       local_writer->finish_dump_segment();
2985       local_writer->flush();
2986     }
2987     if (is_vm_dumper(worker_id)) {
2988       _dumper_controller->wait_all_dumpers_complete();
2989     } else {
2990       _dumper_controller->dumper_complete(local_writer, writer());
2991       delete local_writer;
2992       return;
2993     }
2994   }
2995   // At this point, all fragments of the heapdump have been written to separate files.
2996   // We need to merge them into a complete heapdump and write HPROF_HEAP_DUMP_END at that time.
2997 }
2998 
2999 void VM_HeapDumper::dump_stack_traces() {
3000   // write a HPROF_TRACE record without any frames to be referenced as object alloc sites
3001   DumperSupport::write_header(writer(), HPROF_TRACE, 3 * sizeof(u4));
3002   writer()->write_u4((u4)STACK_TRACE_ID);
3003   writer()->write_u4(0);                    // thread number
3004   writer()->write_u4(0);                    // frame count
3005 
3006   // max number if every platform thread is carrier with mounted virtual thread
3007   _thread_dumpers = NEW_C_HEAP_ARRAY(ThreadDumper*, Threads::number_of_threads() * 2, mtInternal);
3008 
3009   for (JavaThreadIteratorWithHandle jtiwh; JavaThread * thread = jtiwh.next(); ) {
3010     if (ThreadDumper::should_dump_pthread(thread)) {
3011       bool add_oom_frame = is_oom_thread(thread);
3012 
3013       oop mounted_vt = thread->is_vthread_mounted() ? thread->vthread() : nullptr;
3014       if (mounted_vt != nullptr && !ThreadDumper::should_dump_vthread(mounted_vt)) {
3015         mounted_vt = nullptr;
3016       }
3017 
3018       // mounted vthread (if any)
3019       if (mounted_vt != nullptr) {
3020         ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::MountedVirtual, thread, mounted_vt);
3021         _thread_dumpers[_thread_dumpers_count++] = thread_dumper;
3022         if (add_oom_frame) {
3023           thread_dumper->add_oom_frame(_oome_constructor);
3024           // we add oom frame to the VT stack, don't add it to the carrier thread stack
3025           add_oom_frame = false;
3026         }
3027         thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num);
3028         thread_dumper->dump_stack_traces(writer(), _klass_map);
3029       }
3030 
3031       // platform or carrier thread
3032       ThreadDumper* thread_dumper = new ThreadDumper(ThreadDumper::ThreadType::Platform, thread, thread->threadObj());
3033       _thread_dumpers[_thread_dumpers_count++] = thread_dumper;
3034       if (add_oom_frame) {
3035         thread_dumper->add_oom_frame(_oome_constructor);
3036       }
3037       thread_dumper->init_serial_nums(&_thread_serial_num, &_frame_serial_num);
3038       thread_dumper->dump_stack_traces(writer(), _klass_map);
3039     }
3040   }
3041 }
3042 
3043 // dump the heap to given path.
3044 int HeapDumper::dump(const char* path, outputStream* out, int compression, bool overwrite, uint num_dump_threads) {
3045   assert(path != nullptr && strlen(path) > 0, "path missing");
3046 
3047   // print message in interactive case
3048   if (out != nullptr) {
3049     out->print_cr("Dumping heap to %s ...", path);
3050     timer()->start();
3051   }
3052   // create JFR event
3053   EventHeapDump event;
3054 
3055   AbstractCompressor* compressor = nullptr;
3056 
3057   if (compression > 0) {
3058     compressor = new (std::nothrow) GZipCompressor(compression);
3059 
3060     if (compressor == nullptr) {
3061       set_error("Could not allocate gzip compressor");
3062       return -1;
3063     }
3064   }
3065 
3066   DumpWriter writer(path, overwrite, compressor);
3067 
3068   if (writer.error() != nullptr) {
3069     set_error(writer.error());
3070     if (out != nullptr) {
3071       out->print_cr("Unable to create %s: %s", path,
3072         (error() != nullptr) ? error() : "reason unknown");
3073     }
3074     return -1;
3075   }
3076 
3077   // generate the segmented heap dump into separate files
3078   VM_HeapDumper dumper(&writer, _gc_before_heap_dump, _oome, num_dump_threads);
3079   VMThread::execute(&dumper);
3080 
3081   // record any error that the writer may have encountered
3082   set_error(writer.error());
3083 
3084   // For serial dump, once VM_HeapDumper completes, the whole heap dump process
3085   // is done, no further phases needed. For parallel dump, the whole heap dump
3086   // process is done in two phases
3087   //
3088   // Phase 1: Concurrent threads directly write heap data to multiple heap files.
3089   //          This is done by VM_HeapDumper, which is performed within safepoint.
3090   //
3091   // Phase 2: Merge multiple heap files into one complete heap dump file.
3092   //          This is done by DumpMerger, which is performed outside safepoint
3093   if (dumper.is_parallel_dump()) {
3094     DumpMerger merger(path, &writer, dumper.inlined_objects(), dumper.dump_seq());
3095     Thread* current_thread = Thread::current();
3096     if (current_thread->is_AttachListener_thread()) {
3097       // perform heapdump file merge operation in the current thread prevents us
3098       // from occupying the VM Thread, which in turn affects the occurrence of
3099       // GC and other VM operations.
3100       merger.do_merge();
3101     } else {
3102       // otherwise, performs it by VM thread
3103       VM_HeapDumpMerge op(&merger);
3104       VMThread::execute(&op);
3105     }
3106     set_error(writer.error());
3107   }
3108 
3109   // emit JFR event
3110   if (error() == nullptr) {
3111     event.set_destination(path);
3112     event.set_gcBeforeDump(_gc_before_heap_dump);
3113     event.set_size(writer.bytes_written());
3114     event.set_onOutOfMemoryError(_oome);
3115     event.set_overwrite(overwrite);
3116     event.set_compression(compression);
3117     event.commit();
3118   } else {
3119     log_debug(cds, heap)("Error %s while dumping heap", error());
3120   }
3121 
3122   // print message in interactive case
3123   if (out != nullptr) {
3124     timer()->stop();
3125     if (error() == nullptr) {
3126       out->print_cr("Heap dump file created [" JULONG_FORMAT " bytes in %3.3f secs]",
3127                     writer.bytes_written(), timer()->seconds());
3128     } else {
3129       out->print_cr("Dump file is incomplete: %s", writer.error());
3130     }
3131   }
3132 
3133   if (compressor != nullptr) {
3134     delete compressor;
3135   }
3136   return (writer.error() == nullptr) ? 0 : -1;
3137 }
3138 
3139 // stop timer (if still active), and free any error string we might be holding
3140 HeapDumper::~HeapDumper() {
3141   if (timer()->is_active()) {
3142     timer()->stop();
3143   }
3144   set_error(nullptr);
3145 }
3146 
3147 
3148 // returns the error string (resource allocated), or null
3149 char* HeapDumper::error_as_C_string() const {
3150   if (error() != nullptr) {
3151     char* str = NEW_RESOURCE_ARRAY(char, strlen(error())+1);
3152     strcpy(str, error());
3153     return str;
3154   } else {
3155     return nullptr;
3156   }
3157 }
3158 
3159 // set the error string
3160 void HeapDumper::set_error(char const* error) {
3161   if (_error != nullptr) {
3162     os::free(_error);
3163   }
3164   if (error == nullptr) {
3165     _error = nullptr;
3166   } else {
3167     _error = os::strdup(error);
3168     assert(_error != nullptr, "allocation failure");
3169   }
3170 }
3171 
3172 // Called by out-of-memory error reporting by a single Java thread
3173 // outside of a JVM safepoint
3174 void HeapDumper::dump_heap_from_oome() {
3175   HeapDumper::dump_heap(true);
3176 }
3177 
3178 // Called by error reporting by a single Java thread outside of a JVM safepoint,
3179 // or by heap dumping by the VM thread during a (GC) safepoint. Thus, these various
3180 // callers are strictly serialized and guaranteed not to interfere below. For more
3181 // general use, however, this method will need modification to prevent
3182 // inteference when updating the static variables base_path and dump_file_seq below.
3183 void HeapDumper::dump_heap() {
3184   HeapDumper::dump_heap(false);
3185 }
3186 
3187 void HeapDumper::dump_heap(bool oome) {
3188   static char base_path[JVM_MAXPATHLEN] = {'\0'};
3189   static uint dump_file_seq = 0;
3190   char* my_path;
3191   const int max_digit_chars = 20;
3192 
3193   const char* dump_file_name = "java_pid";
3194   const char* dump_file_ext  = HeapDumpGzipLevel > 0 ? ".hprof.gz" : ".hprof";
3195 
3196   // The dump file defaults to java_pid<pid>.hprof in the current working
3197   // directory. HeapDumpPath=<file> can be used to specify an alternative
3198   // dump file name or a directory where dump file is created.
3199   if (dump_file_seq == 0) { // first time in, we initialize base_path
3200     // Calculate potentially longest base path and check if we have enough
3201     // allocated statically.
3202     const size_t total_length =
3203                       (HeapDumpPath == nullptr ? 0 : strlen(HeapDumpPath)) +
3204                       strlen(os::file_separator()) + max_digit_chars +
3205                       strlen(dump_file_name) + strlen(dump_file_ext) + 1;
3206     if (total_length > sizeof(base_path)) {
3207       warning("Cannot create heap dump file.  HeapDumpPath is too long.");
3208       return;
3209     }
3210 
3211     bool use_default_filename = true;
3212     if (HeapDumpPath == nullptr || HeapDumpPath[0] == '\0') {
3213       // HeapDumpPath=<file> not specified
3214     } else {
3215       strcpy(base_path, HeapDumpPath);
3216       // check if the path is a directory (must exist)
3217       DIR* dir = os::opendir(base_path);
3218       if (dir == nullptr) {
3219         use_default_filename = false;
3220       } else {
3221         // HeapDumpPath specified a directory. We append a file separator
3222         // (if needed).
3223         os::closedir(dir);
3224         size_t fs_len = strlen(os::file_separator());
3225         if (strlen(base_path) >= fs_len) {
3226           char* end = base_path;
3227           end += (strlen(base_path) - fs_len);
3228           if (strcmp(end, os::file_separator()) != 0) {
3229             strcat(base_path, os::file_separator());
3230           }
3231         }
3232       }
3233     }
3234     // If HeapDumpPath wasn't a file name then we append the default name
3235     if (use_default_filename) {
3236       const size_t dlen = strlen(base_path);  // if heap dump dir specified
3237       jio_snprintf(&base_path[dlen], sizeof(base_path)-dlen, "%s%d%s",
3238                    dump_file_name, os::current_process_id(), dump_file_ext);
3239     }
3240     const size_t len = strlen(base_path) + 1;
3241     my_path = (char*)os::malloc(len, mtInternal);
3242     if (my_path == nullptr) {
3243       warning("Cannot create heap dump file.  Out of system memory.");
3244       return;
3245     }
3246     strncpy(my_path, base_path, len);
3247   } else {
3248     // Append a sequence number id for dumps following the first
3249     const size_t len = strlen(base_path) + max_digit_chars + 2; // for '.' and \0
3250     my_path = (char*)os::malloc(len, mtInternal);
3251     if (my_path == nullptr) {
3252       warning("Cannot create heap dump file.  Out of system memory.");
3253       return;
3254     }
3255     jio_snprintf(my_path, len, "%s.%d", base_path, dump_file_seq);
3256   }
3257   dump_file_seq++;   // increment seq number for next time we dump
3258 
3259   HeapDumper dumper(false /* no GC before heap dump */,
3260                     oome  /* pass along out-of-memory-error flag */);
3261   dumper.dump(my_path, tty, HeapDumpGzipLevel);
3262   os::free(my_path);
3263 }