1 /*
2 * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderData.inline.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/vmClasses.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "gc/shared/gcLocker.hpp"
33 #include "gc/shared/gcVMOperations.hpp"
34 #include "gc/shared/workerThread.hpp"
35 #include "jfr/jfrEvents.hpp"
36 #include "jvm.h"
37 #include "memory/allocation.inline.hpp"
38 #include "memory/resourceArea.hpp"
39 #include "memory/universe.hpp"
40 #include "oops/klass.inline.hpp"
41 #include "oops/objArrayKlass.hpp"
42 #include "oops/objArrayOop.inline.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/typeArrayOop.inline.hpp"
45 #include "runtime/frame.inline.hpp"
46 #include "runtime/handles.inline.hpp"
47 #include "runtime/javaCalls.hpp"
48 #include "runtime/javaThread.inline.hpp"
49 #include "runtime/jniHandles.hpp"
50 #include "runtime/os.hpp"
51 #include "runtime/reflectionUtils.hpp"
52 #include "runtime/threads.hpp"
53 #include "runtime/threadSMR.hpp"
54 #include "runtime/vframe.hpp"
55 #include "runtime/vmOperations.hpp"
56 #include "runtime/vmThread.hpp"
57 #include "services/heapDumper.hpp"
58 #include "services/heapDumperCompression.hpp"
59 #include "services/threadService.hpp"
60 #include "utilities/macros.hpp"
61 #include "utilities/ostream.hpp"
62
63 /*
64 * HPROF binary format - description copied from:
65 * src/share/demo/jvmti/hprof/hprof_io.c
66 *
67 *
68 * header "JAVA PROFILE 1.0.2" (0-terminated)
69 *
70 * u4 size of identifiers. Identifiers are used to represent
71 * UTF8 strings, objects, stack traces, etc. They usually
72 * have the same size as host pointers.
73 * u4 high word
74 * u4 low word number of milliseconds since 0:00 GMT, 1/1/70
75 * [record]* a sequence of records.
76 *
77 *
78 * Record format:
79 *
80 * u1 a TAG denoting the type of the record
81 * u4 number of *microseconds* since the time stamp in the
82 * header. (wraps around in a little more than an hour)
83 * u4 number of bytes *remaining* in the record. Note that
84 * this number excludes the tag and the length field itself.
85 * [u1]* BODY of the record (a sequence of bytes)
86 *
87 *
88 * The following TAGs are supported:
89 *
90 * TAG BODY notes
91 *----------------------------------------------------------
92 * HPROF_UTF8 a UTF8-encoded name
93 *
94 * id name ID
95 * [u1]* UTF8 characters (no trailing zero)
96 *
97 * HPROF_LOAD_CLASS a newly loaded class
98 *
99 * u4 class serial number (> 0)
100 * id class object ID
101 * u4 stack trace serial number
102 * id class name ID
103 *
104 * HPROF_UNLOAD_CLASS an unloading class
105 *
106 * u4 class serial_number
107 *
108 * HPROF_FRAME a Java stack frame
109 *
110 * id stack frame ID
111 * id method name ID
112 * id method signature ID
113 * id source file name ID
114 * u4 class serial number
115 * i4 line number. >0: normal
116 * -1: unknown
117 * -2: compiled method
118 * -3: native method
119 *
120 * HPROF_TRACE a Java stack trace
121 *
122 * u4 stack trace serial number
123 * u4 thread serial number
124 * u4 number of frames
125 * [id]* stack frame IDs
126 *
127 *
128 * HPROF_ALLOC_SITES a set of heap allocation sites, obtained after GC
129 *
130 * u2 flags 0x0001: incremental vs. complete
131 * 0x0002: sorted by allocation vs. live
132 * 0x0004: whether to force a GC
133 * u4 cutoff ratio
134 * u4 total live bytes
135 * u4 total live instances
136 * u8 total bytes allocated
137 * u8 total instances allocated
138 * u4 number of sites that follow
139 * [u1 is_array: 0: normal object
140 * 2: object array
141 * 4: boolean array
142 * 5: char array
143 * 6: float array
144 * 7: double array
145 * 8: byte array
146 * 9: short array
147 * 10: int array
148 * 11: long array
149 * u4 class serial number (may be zero during startup)
150 * u4 stack trace serial number
151 * u4 number of bytes alive
152 * u4 number of instances alive
153 * u4 number of bytes allocated
154 * u4]* number of instance allocated
155 *
156 * HPROF_START_THREAD a newly started thread.
157 *
158 * u4 thread serial number (> 0)
159 * id thread object ID
160 * u4 stack trace serial number
161 * id thread name ID
162 * id thread group name ID
163 * id thread group parent name ID
164 *
165 * HPROF_END_THREAD a terminating thread.
166 *
167 * u4 thread serial number
168 *
169 * HPROF_HEAP_SUMMARY heap summary
170 *
171 * u4 total live bytes
172 * u4 total live instances
173 * u8 total bytes allocated
174 * u8 total instances allocated
175 *
176 * HPROF_HEAP_DUMP denote a heap dump
177 *
178 * [heap dump sub-records]*
179 *
180 * There are four kinds of heap dump sub-records:
181 *
182 * u1 sub-record type
183 *
184 * HPROF_GC_ROOT_UNKNOWN unknown root
185 *
186 * id object ID
187 *
188 * HPROF_GC_ROOT_THREAD_OBJ thread object
189 *
190 * id thread object ID (may be 0 for a
191 * thread newly attached through JNI)
192 * u4 thread sequence number
193 * u4 stack trace sequence number
194 *
195 * HPROF_GC_ROOT_JNI_GLOBAL JNI global ref root
196 *
197 * id object ID
198 * id JNI global ref ID
199 *
200 * HPROF_GC_ROOT_JNI_LOCAL JNI local ref
201 *
202 * id object ID
203 * u4 thread serial number
204 * u4 frame # in stack trace (-1 for empty)
205 *
206 * HPROF_GC_ROOT_JAVA_FRAME Java stack frame
207 *
208 * id object ID
209 * u4 thread serial number
210 * u4 frame # in stack trace (-1 for empty)
211 *
212 * HPROF_GC_ROOT_NATIVE_STACK Native stack
213 *
214 * id object ID
215 * u4 thread serial number
216 *
217 * HPROF_GC_ROOT_STICKY_CLASS System class
218 *
219 * id object ID
220 *
221 * HPROF_GC_ROOT_THREAD_BLOCK Reference from thread block
222 *
223 * id object ID
224 * u4 thread serial number
225 *
226 * HPROF_GC_ROOT_MONITOR_USED Busy monitor
227 *
228 * id object ID
229 *
230 * HPROF_GC_CLASS_DUMP dump of a class object
231 *
232 * id class object ID
233 * u4 stack trace serial number
234 * id super class object ID
235 * id class loader object ID
236 * id signers object ID
237 * id protection domain object ID
238 * id reserved
239 * id reserved
240 *
241 * u4 instance size (in bytes)
242 *
243 * u2 size of constant pool
244 * [u2, constant pool index,
245 * ty, type
246 * 2: object
247 * 4: boolean
248 * 5: char
249 * 6: float
250 * 7: double
251 * 8: byte
252 * 9: short
253 * 10: int
254 * 11: long
255 * vl]* and value
256 *
257 * u2 number of static fields
258 * [id, static field name,
259 * ty, type,
260 * vl]* and value
261 *
262 * u2 number of inst. fields (not inc. super)
263 * [id, instance field name,
264 * ty]* type
265 *
266 * HPROF_GC_INSTANCE_DUMP dump of a normal object
267 *
268 * id object ID
269 * u4 stack trace serial number
270 * id class object ID
271 * u4 number of bytes that follow
272 * [vl]* instance field values (class, followed
273 * by super, super's super ...)
274 *
275 * HPROF_GC_OBJ_ARRAY_DUMP dump of an object array
276 *
277 * id array object ID
278 * u4 stack trace serial number
279 * u4 number of elements
280 * id array class ID
281 * [id]* elements
282 *
283 * HPROF_GC_PRIM_ARRAY_DUMP dump of a primitive array
284 *
285 * id array object ID
286 * u4 stack trace serial number
287 * u4 number of elements
288 * u1 element type
289 * 4: boolean array
290 * 5: char array
291 * 6: float array
292 * 7: double array
293 * 8: byte array
294 * 9: short array
295 * 10: int array
296 * 11: long array
297 * [u1]* elements
298 *
299 * HPROF_CPU_SAMPLES a set of sample traces of running threads
300 *
301 * u4 total number of samples
302 * u4 # of traces
303 * [u4 # of samples
304 * u4]* stack trace serial number
305 *
306 * HPROF_CONTROL_SETTINGS the settings of on/off switches
307 *
308 * u4 0x00000001: alloc traces on/off
309 * 0x00000002: cpu sampling on/off
310 * u2 stack trace depth
311 *
312 *
313 * When the header is "JAVA PROFILE 1.0.2" a heap dump can optionally
314 * be generated as a sequence of heap dump segments. This sequence is
315 * terminated by an end record. The additional tags allowed by format
316 * "JAVA PROFILE 1.0.2" are:
317 *
318 * HPROF_HEAP_DUMP_SEGMENT denote a heap dump segment
319 *
320 * [heap dump sub-records]*
321 * The same sub-record types allowed by HPROF_HEAP_DUMP
322 *
323 * HPROF_HEAP_DUMP_END denotes the end of a heap dump
324 *
325 */
326
327
328 // HPROF tags
329
330 enum hprofTag : u1 {
331 // top-level records
332 HPROF_UTF8 = 0x01,
333 HPROF_LOAD_CLASS = 0x02,
334 HPROF_UNLOAD_CLASS = 0x03,
335 HPROF_FRAME = 0x04,
336 HPROF_TRACE = 0x05,
337 HPROF_ALLOC_SITES = 0x06,
338 HPROF_HEAP_SUMMARY = 0x07,
339 HPROF_START_THREAD = 0x0A,
340 HPROF_END_THREAD = 0x0B,
341 HPROF_HEAP_DUMP = 0x0C,
342 HPROF_CPU_SAMPLES = 0x0D,
343 HPROF_CONTROL_SETTINGS = 0x0E,
344
345 // 1.0.2 record types
346 HPROF_HEAP_DUMP_SEGMENT = 0x1C,
347 HPROF_HEAP_DUMP_END = 0x2C,
348
349 // field types
350 HPROF_ARRAY_OBJECT = 0x01,
351 HPROF_NORMAL_OBJECT = 0x02,
352 HPROF_BOOLEAN = 0x04,
353 HPROF_CHAR = 0x05,
354 HPROF_FLOAT = 0x06,
355 HPROF_DOUBLE = 0x07,
356 HPROF_BYTE = 0x08,
357 HPROF_SHORT = 0x09,
358 HPROF_INT = 0x0A,
359 HPROF_LONG = 0x0B,
360
361 // data-dump sub-records
362 HPROF_GC_ROOT_UNKNOWN = 0xFF,
363 HPROF_GC_ROOT_JNI_GLOBAL = 0x01,
364 HPROF_GC_ROOT_JNI_LOCAL = 0x02,
365 HPROF_GC_ROOT_JAVA_FRAME = 0x03,
366 HPROF_GC_ROOT_NATIVE_STACK = 0x04,
367 HPROF_GC_ROOT_STICKY_CLASS = 0x05,
368 HPROF_GC_ROOT_THREAD_BLOCK = 0x06,
369 HPROF_GC_ROOT_MONITOR_USED = 0x07,
370 HPROF_GC_ROOT_THREAD_OBJ = 0x08,
371 HPROF_GC_CLASS_DUMP = 0x20,
372 HPROF_GC_INSTANCE_DUMP = 0x21,
373 HPROF_GC_OBJ_ARRAY_DUMP = 0x22,
374 HPROF_GC_PRIM_ARRAY_DUMP = 0x23
375 };
376
377 // Default stack trace ID (used for dummy HPROF_TRACE record)
378 enum {
379 STACK_TRACE_ID = 1,
380 INITIAL_CLASS_COUNT = 200
381 };
382
383 // Supports I/O operations for a dump
384 // Base class for dump and parallel dump
385 class AbstractDumpWriter : public StackObj {
386 protected:
387 enum {
388 io_buffer_max_size = 1*M,
389 io_buffer_max_waste = 10*K,
390 dump_segment_header_size = 9
391 };
392
393 char* _buffer; // internal buffer
394 size_t _size;
395 size_t _pos;
396
397 bool _in_dump_segment; // Are we currently in a dump segment?
398 bool _is_huge_sub_record; // Are we writing a sub-record larger than the buffer size?
399 DEBUG_ONLY(size_t _sub_record_left;) // The bytes not written for the current sub-record.
400 DEBUG_ONLY(bool _sub_record_ended;) // True if we have called the end_sub_record().
401
402 virtual void flush(bool force = false) = 0;
403
404 char* buffer() const { return _buffer; }
405 size_t buffer_size() const { return _size; }
406 void set_position(size_t pos) { _pos = pos; }
407
408 // Can be called if we have enough room in the buffer.
409 void write_fast(const void* s, size_t len);
410
411 // Returns true if we have enough room in the buffer for 'len' bytes.
412 bool can_write_fast(size_t len);
413
414 void write_address(address a);
415
416 public:
417 AbstractDumpWriter() :
418 _buffer(nullptr),
419 _size(io_buffer_max_size),
420 _pos(0),
421 _in_dump_segment(false) { }
422
423 // total number of bytes written to the disk
424 virtual julong bytes_written() const = 0;
425 virtual char const* error() const = 0;
426
427 size_t position() const { return _pos; }
428 // writer functions
429 virtual void write_raw(const void* s, size_t len);
430 void write_u1(u1 x);
431 void write_u2(u2 x);
432 void write_u4(u4 x);
433 void write_u8(u8 x);
434 void write_objectID(oop o);
435 void write_rootID(oop* p);
436 void write_symbolID(Symbol* o);
437 void write_classID(Klass* k);
438 void write_id(u4 x);
439
440 // Start a new sub-record. Starts a new heap dump segment if needed.
441 void start_sub_record(u1 tag, u4 len);
442 // Ends the current sub-record.
443 void end_sub_record();
444 // Finishes the current dump segment if not already finished.
445 void finish_dump_segment(bool force_flush = false);
446 // Refresh to get new buffer
447 void refresh() {
448 assert (_in_dump_segment ==false, "Sanity check");
449 _buffer = nullptr;
450 _size = io_buffer_max_size;
451 _pos = 0;
452 // Force flush to guarantee data from parallel dumper are written.
453 flush(true);
454 }
455 // Called when finished to release the threads.
456 virtual void deactivate() = 0;
457 };
458
459 void AbstractDumpWriter::write_fast(const void* s, size_t len) {
460 assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
461 assert(buffer_size() - position() >= len, "Must fit");
462 debug_only(_sub_record_left -= len);
463 memcpy(buffer() + position(), s, len);
464 set_position(position() + len);
465 }
466
467 bool AbstractDumpWriter::can_write_fast(size_t len) {
468 return buffer_size() - position() >= len;
469 }
470
471 // write raw bytes
472 void AbstractDumpWriter::write_raw(const void* s, size_t len) {
473 assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
474 debug_only(_sub_record_left -= len);
475
476 // flush buffer to make room.
477 while (len > buffer_size() - position()) {
478 assert(!_in_dump_segment || _is_huge_sub_record,
479 "Cannot overflow in non-huge sub-record.");
480 size_t to_write = buffer_size() - position();
481 memcpy(buffer() + position(), s, to_write);
482 s = (void*) ((char*) s + to_write);
483 len -= to_write;
484 set_position(position() + to_write);
485 flush();
486 }
487
488 memcpy(buffer() + position(), s, len);
489 set_position(position() + len);
490 }
491
492 // Makes sure we inline the fast write into the write_u* functions. This is a big speedup.
493 #define WRITE_KNOWN_TYPE(p, len) do { if (can_write_fast((len))) write_fast((p), (len)); \
494 else write_raw((p), (len)); } while (0)
495
496 void AbstractDumpWriter::write_u1(u1 x) {
497 WRITE_KNOWN_TYPE(&x, 1);
498 }
499
500 void AbstractDumpWriter::write_u2(u2 x) {
501 u2 v;
502 Bytes::put_Java_u2((address)&v, x);
503 WRITE_KNOWN_TYPE(&v, 2);
504 }
505
506 void AbstractDumpWriter::write_u4(u4 x) {
507 u4 v;
508 Bytes::put_Java_u4((address)&v, x);
509 WRITE_KNOWN_TYPE(&v, 4);
510 }
511
512 void AbstractDumpWriter::write_u8(u8 x) {
513 u8 v;
514 Bytes::put_Java_u8((address)&v, x);
515 WRITE_KNOWN_TYPE(&v, 8);
516 }
517
518 void AbstractDumpWriter::write_address(address a) {
519 #ifdef _LP64
520 write_u8((u8)a);
521 #else
522 write_u4((u4)a);
523 #endif
524 }
525
526 void AbstractDumpWriter::write_objectID(oop o) {
527 write_address(cast_from_oop<address>(o));
528 }
529
530 void AbstractDumpWriter::write_rootID(oop* p) {
531 write_address((address)p);
532 }
533
534 void AbstractDumpWriter::write_symbolID(Symbol* s) {
535 write_address((address)((uintptr_t)s));
536 }
537
538 void AbstractDumpWriter::write_id(u4 x) {
539 #ifdef _LP64
540 write_u8((u8) x);
541 #else
542 write_u4(x);
543 #endif
544 }
545
546 // We use java mirror as the class ID
547 void AbstractDumpWriter::write_classID(Klass* k) {
548 write_objectID(k->java_mirror());
549 }
550
551 void AbstractDumpWriter::finish_dump_segment(bool force_flush) {
552 if (_in_dump_segment) {
553 assert(_sub_record_left == 0, "Last sub-record not written completely");
554 assert(_sub_record_ended, "sub-record must have ended");
555
556 // Fix up the dump segment length if we haven't written a huge sub-record last
557 // (in which case the segment length was already set to the correct value initially).
558 if (!_is_huge_sub_record) {
559 assert(position() > dump_segment_header_size, "Dump segment should have some content");
560 Bytes::put_Java_u4((address) (buffer() + 5),
561 (u4) (position() - dump_segment_header_size));
562 } else {
563 // Finish process huge sub record
564 // Set _is_huge_sub_record to false so the parallel dump writer can flush data to file.
565 _is_huge_sub_record = false;
566 }
567
568 _in_dump_segment = false;
569 flush(force_flush);
570 }
571 }
572
573 void AbstractDumpWriter::start_sub_record(u1 tag, u4 len) {
574 if (!_in_dump_segment) {
575 if (position() > 0) {
576 flush();
577 }
578
579 assert(position() == 0 && buffer_size() > dump_segment_header_size, "Must be at the start");
580
581 write_u1(HPROF_HEAP_DUMP_SEGMENT);
582 write_u4(0); // timestamp
583 // Will be fixed up later if we add more sub-records. If this is a huge sub-record,
584 // this is already the correct length, since we don't add more sub-records.
585 write_u4(len);
586 assert(Bytes::get_Java_u4((address)(buffer() + 5)) == len, "Inconsistent size!");
587 _in_dump_segment = true;
588 _is_huge_sub_record = len > buffer_size() - dump_segment_header_size;
589 } else if (_is_huge_sub_record || (len > buffer_size() - position())) {
590 // This object will not fit in completely or the last sub-record was huge.
591 // Finish the current segment and try again.
592 finish_dump_segment();
593 start_sub_record(tag, len);
594
595 return;
596 }
597
598 debug_only(_sub_record_left = len);
599 debug_only(_sub_record_ended = false);
600
601 write_u1(tag);
602 }
603
604 void AbstractDumpWriter::end_sub_record() {
605 assert(_in_dump_segment, "must be in dump segment");
606 assert(_sub_record_left == 0, "sub-record not written completely");
607 assert(!_sub_record_ended, "Must not have ended yet");
608 debug_only(_sub_record_ended = true);
609 }
610
611 // Supports I/O operations for a dump
612
613 class DumpWriter : public AbstractDumpWriter {
614 private:
615 CompressionBackend _backend; // Does the actual writing.
616 protected:
617 void flush(bool force = false) override;
618
619 public:
620 // Takes ownership of the writer and compressor.
621 DumpWriter(AbstractWriter* writer, AbstractCompressor* compressor);
622
623 // total number of bytes written to the disk
624 julong bytes_written() const override { return (julong) _backend.get_written(); }
625
626 char const* error() const override { return _backend.error(); }
627
628 // Called by threads used for parallel writing.
629 void writer_loop() { _backend.thread_loop(); }
630 // Called when finish to release the threads.
631 void deactivate() override { flush(); _backend.deactivate(); }
632 // Get the backend pointer, used by parallel dump writer.
633 CompressionBackend* backend_ptr() { return &_backend; }
634
635 };
636
637 // Check for error after constructing the object and destroy it in case of an error.
638 DumpWriter::DumpWriter(AbstractWriter* writer, AbstractCompressor* compressor) :
639 AbstractDumpWriter(),
640 _backend(writer, compressor, io_buffer_max_size, io_buffer_max_waste) {
641 flush();
642 }
643
644 // flush any buffered bytes to the file
645 void DumpWriter::flush(bool force) {
646 _backend.get_new_buffer(&_buffer, &_pos, &_size, force);
647 }
648
649 // Buffer queue used for parallel dump.
650 struct ParWriterBufferQueueElem {
651 char* _buffer;
652 size_t _used;
653 ParWriterBufferQueueElem* _next;
654 };
655
656 class ParWriterBufferQueue : public CHeapObj<mtInternal> {
657 private:
658 ParWriterBufferQueueElem* _head;
659 ParWriterBufferQueueElem* _tail;
660 uint _length;
661 public:
662 ParWriterBufferQueue() : _head(nullptr), _tail(nullptr), _length(0) { }
663
664 void enqueue(ParWriterBufferQueueElem* entry) {
665 if (_head == nullptr) {
666 assert(is_empty() && _tail == nullptr, "Sanity check");
667 _head = _tail = entry;
668 } else {
669 assert ((_tail->_next == nullptr && _tail->_buffer != nullptr), "Buffer queue is polluted");
670 _tail->_next = entry;
671 _tail = entry;
672 }
673 _length++;
674 assert(_tail->_next == nullptr, "Buffer queue is polluted");
675 }
676
677 ParWriterBufferQueueElem* dequeue() {
678 if (_head == nullptr) return nullptr;
679 ParWriterBufferQueueElem* entry = _head;
680 assert (entry->_buffer != nullptr, "polluted buffer in writer list");
681 _head = entry->_next;
682 if (_head == nullptr) {
683 _tail = nullptr;
684 }
685 entry->_next = nullptr;
686 _length--;
687 return entry;
688 }
689
690 bool is_empty() {
691 return _length == 0;
692 }
693
694 uint length() { return _length; }
695 };
696
697 // Support parallel heap dump.
698 class ParDumpWriter : public AbstractDumpWriter {
699 private:
700 // Lock used to guarantee the integrity of multiple buffers writing.
701 static Monitor* _lock;
702 // Pointer of backend from global DumpWriter.
703 CompressionBackend* _backend_ptr;
704 char const * _err;
705 ParWriterBufferQueue* _buffer_queue;
706 size_t _internal_buffer_used;
707 char* _buffer_base;
708 bool _split_data;
709 static const uint BackendFlushThreshold = 2;
710 protected:
711 void flush(bool force = false) override {
712 assert(_pos != 0, "must not be zero");
713 if (_pos != 0) {
714 refresh_buffer();
715 }
716
717 if (_split_data || _is_huge_sub_record) {
718 return;
719 }
720
721 if (should_flush_buf_list(force)) {
722 assert(!_in_dump_segment && !_split_data && !_is_huge_sub_record, "incomplete data send to backend!\n");
723 flush_to_backend(force);
724 }
725 }
726
727 public:
728 // Check for error after constructing the object and destroy it in case of an error.
729 ParDumpWriter(DumpWriter* dw) :
730 AbstractDumpWriter(),
731 _backend_ptr(dw->backend_ptr()),
732 _buffer_queue((new (std::nothrow) ParWriterBufferQueue())),
733 _buffer_base(nullptr),
734 _split_data(false) {
735 // prepare internal buffer
736 allocate_internal_buffer();
737 }
738
739 ~ParDumpWriter() {
740 assert(_buffer_queue != nullptr, "Sanity check");
741 assert((_internal_buffer_used == 0) && (_buffer_queue->is_empty()),
742 "All data must be send to backend");
743 if (_buffer_base != nullptr) {
744 os::free(_buffer_base);
745 _buffer_base = nullptr;
746 }
747 delete _buffer_queue;
748 _buffer_queue = nullptr;
749 }
750
751 // total number of bytes written to the disk
752 julong bytes_written() const override { return (julong) _backend_ptr->get_written(); }
753 char const* error() const override { return _err == nullptr ? _backend_ptr->error() : _err; }
754
755 static void before_work() {
756 assert(_lock == nullptr, "ParDumpWriter lock must be initialized only once");
757 _lock = new (std::nothrow) PaddedMonitor(Mutex::safepoint, "ParallelHProfWriter_lock");
758 }
759
760 static void after_work() {
761 assert(_lock != nullptr, "ParDumpWriter lock is not initialized");
762 delete _lock;
763 _lock = nullptr;
764 }
765
766 // write raw bytes
767 void write_raw(const void* s, size_t len) override {
768 assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
769 debug_only(_sub_record_left -= len);
770 assert(!_split_data, "Invalid split data");
771 _split_data = true;
772 // flush buffer to make room.
773 while (len > buffer_size() - position()) {
774 assert(!_in_dump_segment || _is_huge_sub_record,
775 "Cannot overflow in non-huge sub-record.");
776 size_t to_write = buffer_size() - position();
777 memcpy(buffer() + position(), s, to_write);
778 s = (void*) ((char*) s + to_write);
779 len -= to_write;
780 set_position(position() + to_write);
781 flush();
782 }
783 _split_data = false;
784 memcpy(buffer() + position(), s, len);
785 set_position(position() + len);
786 }
787
788 void deactivate() override { flush(true); _backend_ptr->deactivate(); }
789
790 private:
791 void allocate_internal_buffer() {
792 assert(_buffer_queue != nullptr, "Internal buffer queue is not ready when allocate internal buffer");
793 assert(_buffer == nullptr && _buffer_base == nullptr, "current buffer must be null before allocate");
794 _buffer_base = _buffer = (char*)os::malloc(io_buffer_max_size, mtInternal);
795 if (_buffer == nullptr) {
796 set_error("Could not allocate buffer for writer");
797 return;
798 }
799 _pos = 0;
800 _internal_buffer_used = 0;
801 _size = io_buffer_max_size;
802 }
803
804 void set_error(char const* new_error) {
805 if ((new_error != nullptr) && (_err == nullptr)) {
806 _err = new_error;
807 }
808 }
809
810 // Add buffer to internal list
811 void refresh_buffer() {
812 size_t expected_total = _internal_buffer_used + _pos;
813 if (expected_total < io_buffer_max_size - io_buffer_max_waste) {
814 // reuse current buffer.
815 _internal_buffer_used = expected_total;
816 assert(_size - _pos == io_buffer_max_size - expected_total, "illegal resize of buffer");
817 _size -= _pos;
818 _buffer += _pos;
819 _pos = 0;
820
821 return;
822 }
823 // It is not possible here that expected_total is larger than io_buffer_max_size because
824 // of limitation in write_xxx().
825 assert(expected_total <= io_buffer_max_size, "buffer overflow");
826 assert(_buffer - _buffer_base <= io_buffer_max_size, "internal buffer overflow");
827 ParWriterBufferQueueElem* entry =
828 (ParWriterBufferQueueElem*)os::malloc(sizeof(ParWriterBufferQueueElem), mtInternal);
829 if (entry == nullptr) {
830 set_error("Heap dumper can allocate memory");
831 return;
832 }
833 entry->_buffer = _buffer_base;
834 entry->_used = expected_total;
835 entry->_next = nullptr;
836 // add to internal buffer queue
837 _buffer_queue->enqueue(entry);
838 _buffer_base =_buffer = nullptr;
839 allocate_internal_buffer();
840 }
841
842 void reclaim_entry(ParWriterBufferQueueElem* entry) {
843 assert(entry != nullptr && entry->_buffer != nullptr, "Invalid entry to reclaim");
844 os::free(entry->_buffer);
845 entry->_buffer = nullptr;
846 os::free(entry);
847 }
848
849 void flush_buffer(char* buffer, size_t used) {
850 assert(_lock->owner() == Thread::current(), "flush buffer must hold lock");
851 size_t max = io_buffer_max_size;
852 // get_new_buffer
853 _backend_ptr->flush_external_buffer(buffer, used, max);
854 }
855
856 bool should_flush_buf_list(bool force) {
857 return force || _buffer_queue->length() > BackendFlushThreshold;
858 }
859
860 void flush_to_backend(bool force) {
861 // Guarantee there is only one writer updating the backend buffers.
862 MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
863 while (!_buffer_queue->is_empty()) {
864 ParWriterBufferQueueElem* entry = _buffer_queue->dequeue();
865 flush_buffer(entry->_buffer, entry->_used);
866 // Delete buffer and entry.
867 reclaim_entry(entry);
868 entry = nullptr;
869 }
870 assert(_pos == 0, "available buffer must be empty before flush");
871 // Flush internal buffer.
872 if (_internal_buffer_used > 0) {
873 flush_buffer(_buffer_base, _internal_buffer_used);
874 os::free(_buffer_base);
875 _pos = 0;
876 _internal_buffer_used = 0;
877 _buffer_base = _buffer = nullptr;
878 // Allocate internal buffer for future use.
879 allocate_internal_buffer();
880 }
881 }
882 };
883
884 Monitor* ParDumpWriter::_lock = nullptr;
885
886 // Support class with a collection of functions used when dumping the heap
887
888 class DumperSupport : AllStatic {
889 public:
890
891 // write a header of the given type
892 static void write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len);
893
894 // returns hprof tag for the given type signature
895 static hprofTag sig2tag(Symbol* sig);
896 // returns hprof tag for the given basic type
897 static hprofTag type2tag(BasicType type);
898 // Returns the size of the data to write.
899 static u4 sig2size(Symbol* sig);
900
901 // returns the size of the instance of the given class
902 static u4 instance_size(Klass* k);
903
904 // dump a jfloat
905 static void dump_float(AbstractDumpWriter* writer, jfloat f);
906 // dump a jdouble
907 static void dump_double(AbstractDumpWriter* writer, jdouble d);
908 // dumps the raw value of the given field
909 static void dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset);
910 // returns the size of the static fields; also counts the static fields
911 static u4 get_static_fields_size(InstanceKlass* ik, u2& field_count);
912 // dumps static fields of the given class
913 static void dump_static_fields(AbstractDumpWriter* writer, Klass* k);
914 // dump the raw values of the instance fields of the given object
915 static void dump_instance_fields(AbstractDumpWriter* writer, oop o);
916 // get the count of the instance fields for a given class
917 static u2 get_instance_fields_count(InstanceKlass* ik);
918 // dumps the definition of the instance fields for a given class
919 static void dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k);
920 // creates HPROF_GC_INSTANCE_DUMP record for the given object
921 static void dump_instance(AbstractDumpWriter* writer, oop o);
922 // creates HPROF_GC_CLASS_DUMP record for the given instance class
923 static void dump_instance_class(AbstractDumpWriter* writer, Klass* k);
924 // creates HPROF_GC_CLASS_DUMP record for a given array class
925 static void dump_array_class(AbstractDumpWriter* writer, Klass* k);
926
927 // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
928 static void dump_object_array(AbstractDumpWriter* writer, objArrayOop array);
929 // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
930 static void dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array);
931 // create HPROF_FRAME record for the given method and bci
932 static void dump_stack_frame(AbstractDumpWriter* writer, int frame_serial_num, int class_serial_num, Method* m, int bci);
933
934 // check if we need to truncate an array
935 static int calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size);
936
937 // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
938 static void end_of_dump(AbstractDumpWriter* writer);
939
940 static oop mask_dormant_archived_object(oop o) {
941 if (o != nullptr && o->klass()->java_mirror() == nullptr) {
942 // Ignore this object since the corresponding java mirror is not loaded.
943 // Might be a dormant archive object.
944 return nullptr;
945 } else {
946 return o;
947 }
948 }
949 };
950
951 // write a header of the given type
952 void DumperSupport:: write_header(AbstractDumpWriter* writer, hprofTag tag, u4 len) {
953 writer->write_u1(tag);
954 writer->write_u4(0); // current ticks
955 writer->write_u4(len);
956 }
957
958 // returns hprof tag for the given type signature
959 hprofTag DumperSupport::sig2tag(Symbol* sig) {
960 switch (sig->char_at(0)) {
961 case JVM_SIGNATURE_CLASS : return HPROF_NORMAL_OBJECT;
962 case JVM_SIGNATURE_ARRAY : return HPROF_NORMAL_OBJECT;
963 case JVM_SIGNATURE_BYTE : return HPROF_BYTE;
964 case JVM_SIGNATURE_CHAR : return HPROF_CHAR;
965 case JVM_SIGNATURE_FLOAT : return HPROF_FLOAT;
966 case JVM_SIGNATURE_DOUBLE : return HPROF_DOUBLE;
967 case JVM_SIGNATURE_INT : return HPROF_INT;
968 case JVM_SIGNATURE_LONG : return HPROF_LONG;
969 case JVM_SIGNATURE_SHORT : return HPROF_SHORT;
970 case JVM_SIGNATURE_BOOLEAN : return HPROF_BOOLEAN;
971 default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
972 }
973 }
974
975 hprofTag DumperSupport::type2tag(BasicType type) {
976 switch (type) {
977 case T_BYTE : return HPROF_BYTE;
978 case T_CHAR : return HPROF_CHAR;
979 case T_FLOAT : return HPROF_FLOAT;
980 case T_DOUBLE : return HPROF_DOUBLE;
981 case T_INT : return HPROF_INT;
982 case T_LONG : return HPROF_LONG;
983 case T_SHORT : return HPROF_SHORT;
984 case T_BOOLEAN : return HPROF_BOOLEAN;
985 default : ShouldNotReachHere(); /* to shut up compiler */ return HPROF_BYTE;
986 }
987 }
988
989 u4 DumperSupport::sig2size(Symbol* sig) {
990 switch (sig->char_at(0)) {
991 case JVM_SIGNATURE_CLASS:
992 case JVM_SIGNATURE_ARRAY: return sizeof(address);
993 case JVM_SIGNATURE_BOOLEAN:
994 case JVM_SIGNATURE_BYTE: return 1;
995 case JVM_SIGNATURE_SHORT:
996 case JVM_SIGNATURE_CHAR: return 2;
997 case JVM_SIGNATURE_INT:
998 case JVM_SIGNATURE_FLOAT: return 4;
999 case JVM_SIGNATURE_LONG:
1000 case JVM_SIGNATURE_DOUBLE: return 8;
1001 default: ShouldNotReachHere(); /* to shut up compiler */ return 0;
1002 }
1003 }
1004
1005 template<typename T, typename F> T bit_cast(F from) { // replace with the real thing when we can use c++20
1006 T to;
1007 static_assert(sizeof(to) == sizeof(from), "must be of the same size");
1008 memcpy(&to, &from, sizeof(to));
1009 return to;
1010 }
1011
1012 // dump a jfloat
1013 void DumperSupport::dump_float(AbstractDumpWriter* writer, jfloat f) {
1014 if (g_isnan(f)) {
1015 writer->write_u4(0x7fc00000); // collapsing NaNs
1016 } else {
1017 writer->write_u4(bit_cast<u4>(f));
1018 }
1019 }
1020
1021 // dump a jdouble
1022 void DumperSupport::dump_double(AbstractDumpWriter* writer, jdouble d) {
1023 if (g_isnan(d)) {
1024 writer->write_u8(0x7ff80000ull << 32); // collapsing NaNs
1025 } else {
1026 writer->write_u8(bit_cast<u8>(d));
1027 }
1028 }
1029
1030 // dumps the raw value of the given field
1031 void DumperSupport::dump_field_value(AbstractDumpWriter* writer, char type, oop obj, int offset) {
1032 switch (type) {
1033 case JVM_SIGNATURE_CLASS :
1034 case JVM_SIGNATURE_ARRAY : {
1035 oop o = obj->obj_field_access<ON_UNKNOWN_OOP_REF | AS_NO_KEEPALIVE>(offset);
1036 if (o != nullptr && log_is_enabled(Debug, cds, heap) && mask_dormant_archived_object(o) == nullptr) {
1037 ResourceMark rm;
1038 log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)",
1039 p2i(o), o->klass()->external_name(),
1040 p2i(obj), obj->klass()->external_name());
1041 }
1042 o = mask_dormant_archived_object(o);
1043 assert(oopDesc::is_oop_or_null(o), "Expected an oop or nullptr at " PTR_FORMAT, p2i(o));
1044 writer->write_objectID(o);
1045 break;
1046 }
1047 case JVM_SIGNATURE_BYTE : {
1048 jbyte b = obj->byte_field(offset);
1049 writer->write_u1(b);
1050 break;
1051 }
1052 case JVM_SIGNATURE_CHAR : {
1053 jchar c = obj->char_field(offset);
1054 writer->write_u2(c);
1055 break;
1056 }
1057 case JVM_SIGNATURE_SHORT : {
1058 jshort s = obj->short_field(offset);
1059 writer->write_u2(s);
1060 break;
1061 }
1062 case JVM_SIGNATURE_FLOAT : {
1063 jfloat f = obj->float_field(offset);
1064 dump_float(writer, f);
1065 break;
1066 }
1067 case JVM_SIGNATURE_DOUBLE : {
1068 jdouble d = obj->double_field(offset);
1069 dump_double(writer, d);
1070 break;
1071 }
1072 case JVM_SIGNATURE_INT : {
1073 jint i = obj->int_field(offset);
1074 writer->write_u4(i);
1075 break;
1076 }
1077 case JVM_SIGNATURE_LONG : {
1078 jlong l = obj->long_field(offset);
1079 writer->write_u8(l);
1080 break;
1081 }
1082 case JVM_SIGNATURE_BOOLEAN : {
1083 jboolean b = obj->bool_field(offset);
1084 writer->write_u1(b);
1085 break;
1086 }
1087 default : {
1088 ShouldNotReachHere();
1089 break;
1090 }
1091 }
1092 }
1093
1094 // returns the size of the instance of the given class
1095 u4 DumperSupport::instance_size(Klass* k) {
1096 InstanceKlass* ik = InstanceKlass::cast(k);
1097 u4 size = 0;
1098
1099 for (FieldStream fld(ik, false, false); !fld.eos(); fld.next()) {
1100 if (!fld.access_flags().is_static()) {
1101 size += sig2size(fld.signature());
1102 }
1103 }
1104 return size;
1105 }
1106
1107 u4 DumperSupport::get_static_fields_size(InstanceKlass* ik, u2& field_count) {
1108 field_count = 0;
1109 u4 size = 0;
1110
1111 for (FieldStream fldc(ik, true, true); !fldc.eos(); fldc.next()) {
1112 if (fldc.access_flags().is_static()) {
1113 field_count++;
1114 size += sig2size(fldc.signature());
1115 }
1116 }
1117
1118 // Add in resolved_references which is referenced by the cpCache
1119 // The resolved_references is an array per InstanceKlass holding the
1120 // strings and other oops resolved from the constant pool.
1121 oop resolved_references = ik->constants()->resolved_references_or_null();
1122 if (resolved_references != nullptr) {
1123 field_count++;
1124 size += sizeof(address);
1125
1126 // Add in the resolved_references of the used previous versions of the class
1127 // in the case of RedefineClasses
1128 InstanceKlass* prev = ik->previous_versions();
1129 while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
1130 field_count++;
1131 size += sizeof(address);
1132 prev = prev->previous_versions();
1133 }
1134 }
1135
1136 // We write the value itself plus a name and a one byte type tag per field.
1137 return size + field_count * (sizeof(address) + 1);
1138 }
1139
1140 // dumps static fields of the given class
1141 void DumperSupport::dump_static_fields(AbstractDumpWriter* writer, Klass* k) {
1142 InstanceKlass* ik = InstanceKlass::cast(k);
1143
1144 // dump the field descriptors and raw values
1145 for (FieldStream fld(ik, true, true); !fld.eos(); fld.next()) {
1146 if (fld.access_flags().is_static()) {
1147 Symbol* sig = fld.signature();
1148
1149 writer->write_symbolID(fld.name()); // name
1150 writer->write_u1(sig2tag(sig)); // type
1151
1152 // value
1153 dump_field_value(writer, sig->char_at(0), ik->java_mirror(), fld.offset());
1154 }
1155 }
1156
1157 // Add resolved_references for each class that has them
1158 oop resolved_references = ik->constants()->resolved_references_or_null();
1159 if (resolved_references != nullptr) {
1160 writer->write_symbolID(vmSymbols::resolved_references_name()); // name
1161 writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
1162 writer->write_objectID(resolved_references);
1163
1164 // Also write any previous versions
1165 InstanceKlass* prev = ik->previous_versions();
1166 while (prev != nullptr && prev->constants()->resolved_references_or_null() != nullptr) {
1167 writer->write_symbolID(vmSymbols::resolved_references_name()); // name
1168 writer->write_u1(sig2tag(vmSymbols::object_array_signature())); // type
1169 writer->write_objectID(prev->constants()->resolved_references());
1170 prev = prev->previous_versions();
1171 }
1172 }
1173 }
1174
1175 // dump the raw values of the instance fields of the given object
1176 void DumperSupport::dump_instance_fields(AbstractDumpWriter* writer, oop o) {
1177 InstanceKlass* ik = InstanceKlass::cast(o->klass());
1178
1179 for (FieldStream fld(ik, false, false); !fld.eos(); fld.next()) {
1180 if (!fld.access_flags().is_static()) {
1181 Symbol* sig = fld.signature();
1182 dump_field_value(writer, sig->char_at(0), o, fld.offset());
1183 }
1184 }
1185 }
1186
1187 // dumps the definition of the instance fields for a given class
1188 u2 DumperSupport::get_instance_fields_count(InstanceKlass* ik) {
1189 u2 field_count = 0;
1190
1191 for (FieldStream fldc(ik, true, true); !fldc.eos(); fldc.next()) {
1192 if (!fldc.access_flags().is_static()) field_count++;
1193 }
1194
1195 return field_count;
1196 }
1197
1198 // dumps the definition of the instance fields for a given class
1199 void DumperSupport::dump_instance_field_descriptors(AbstractDumpWriter* writer, Klass* k) {
1200 InstanceKlass* ik = InstanceKlass::cast(k);
1201
1202 // dump the field descriptors
1203 for (FieldStream fld(ik, true, true); !fld.eos(); fld.next()) {
1204 if (!fld.access_flags().is_static()) {
1205 Symbol* sig = fld.signature();
1206
1207 writer->write_symbolID(fld.name()); // name
1208 writer->write_u1(sig2tag(sig)); // type
1209 }
1210 }
1211 }
1212
1213 // creates HPROF_GC_INSTANCE_DUMP record for the given object
1214 void DumperSupport::dump_instance(AbstractDumpWriter* writer, oop o) {
1215 InstanceKlass* ik = InstanceKlass::cast(o->klass());
1216 u4 is = instance_size(ik);
1217 u4 size = 1 + sizeof(address) + 4 + sizeof(address) + 4 + is;
1218
1219 writer->start_sub_record(HPROF_GC_INSTANCE_DUMP, size);
1220 writer->write_objectID(o);
1221 writer->write_u4(STACK_TRACE_ID);
1222
1223 // class ID
1224 writer->write_classID(ik);
1225
1226 // number of bytes that follow
1227 writer->write_u4(is);
1228
1229 // field values
1230 dump_instance_fields(writer, o);
1231
1232 writer->end_sub_record();
1233 }
1234
1235 // creates HPROF_GC_CLASS_DUMP record for the given instance class
1236 void DumperSupport::dump_instance_class(AbstractDumpWriter* writer, Klass* k) {
1237 InstanceKlass* ik = InstanceKlass::cast(k);
1238
1239 // We can safepoint and do a heap dump at a point where we have a Klass,
1240 // but no java mirror class has been setup for it. So we need to check
1241 // that the class is at least loaded, to avoid crash from a null mirror.
1242 if (!ik->is_loaded()) {
1243 return;
1244 }
1245
1246 u2 static_fields_count = 0;
1247 u4 static_size = get_static_fields_size(ik, static_fields_count);
1248 u2 instance_fields_count = get_instance_fields_count(ik);
1249 u4 instance_fields_size = instance_fields_count * (sizeof(address) + 1);
1250 u4 size = 1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + static_size + 2 + instance_fields_size;
1251
1252 writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
1253
1254 // class ID
1255 writer->write_classID(ik);
1256 writer->write_u4(STACK_TRACE_ID);
1257
1258 // super class ID
1259 InstanceKlass* java_super = ik->java_super();
1260 if (java_super == nullptr) {
1261 writer->write_objectID(oop(nullptr));
1262 } else {
1263 writer->write_classID(java_super);
1264 }
1265
1266 writer->write_objectID(ik->class_loader());
1267 writer->write_objectID(ik->signers());
1268 writer->write_objectID(ik->protection_domain());
1269
1270 // reserved
1271 writer->write_objectID(oop(nullptr));
1272 writer->write_objectID(oop(nullptr));
1273
1274 // instance size
1275 writer->write_u4(DumperSupport::instance_size(ik));
1276
1277 // size of constant pool - ignored by HAT 1.1
1278 writer->write_u2(0);
1279
1280 // static fields
1281 writer->write_u2(static_fields_count);
1282 dump_static_fields(writer, ik);
1283
1284 // description of instance fields
1285 writer->write_u2(instance_fields_count);
1286 dump_instance_field_descriptors(writer, ik);
1287
1288 writer->end_sub_record();
1289 }
1290
1291 // creates HPROF_GC_CLASS_DUMP record for the given array class
1292 void DumperSupport::dump_array_class(AbstractDumpWriter* writer, Klass* k) {
1293 InstanceKlass* ik = nullptr; // bottom class for object arrays, null for primitive type arrays
1294 if (k->is_objArray_klass()) {
1295 Klass *bk = ObjArrayKlass::cast(k)->bottom_klass();
1296 assert(bk != nullptr, "checking");
1297 if (bk->is_instance_klass()) {
1298 ik = InstanceKlass::cast(bk);
1299 }
1300 }
1301
1302 u4 size = 1 + sizeof(address) + 4 + 6 * sizeof(address) + 4 + 2 + 2 + 2;
1303 writer->start_sub_record(HPROF_GC_CLASS_DUMP, size);
1304 writer->write_classID(k);
1305 writer->write_u4(STACK_TRACE_ID);
1306
1307 // super class of array classes is java.lang.Object
1308 InstanceKlass* java_super = k->java_super();
1309 assert(java_super != nullptr, "checking");
1310 writer->write_classID(java_super);
1311
1312 writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->class_loader());
1313 writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->signers());
1314 writer->write_objectID(ik == nullptr ? oop(nullptr) : ik->protection_domain());
1315
1316 writer->write_objectID(oop(nullptr)); // reserved
1317 writer->write_objectID(oop(nullptr));
1318 writer->write_u4(0); // instance size
1319 writer->write_u2(0); // constant pool
1320 writer->write_u2(0); // static fields
1321 writer->write_u2(0); // instance fields
1322
1323 writer->end_sub_record();
1324
1325 }
1326
1327 // Hprof uses an u4 as record length field,
1328 // which means we need to truncate arrays that are too long.
1329 int DumperSupport::calculate_array_max_length(AbstractDumpWriter* writer, arrayOop array, short header_size) {
1330 BasicType type = ArrayKlass::cast(array->klass())->element_type();
1331 assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type");
1332
1333 int length = array->length();
1334
1335 int type_size;
1336 if (type == T_OBJECT) {
1337 type_size = sizeof(address);
1338 } else {
1339 type_size = type2aelembytes(type);
1340 }
1341
1342 size_t length_in_bytes = (size_t)length * type_size;
1343 uint max_bytes = max_juint - header_size;
1344
1345 if (length_in_bytes > max_bytes) {
1346 length = max_bytes / type_size;
1347 length_in_bytes = (size_t)length * type_size;
1348
1349 warning("cannot dump array of type %s[] with length %d; truncating to length %d",
1350 type2name_tab[type], array->length(), length);
1351 }
1352 return length;
1353 }
1354
1355 // creates HPROF_GC_OBJ_ARRAY_DUMP record for the given object array
1356 void DumperSupport::dump_object_array(AbstractDumpWriter* writer, objArrayOop array) {
1357 // sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID) + sizeof(classID)
1358 short header_size = 1 + 2 * 4 + 2 * sizeof(address);
1359 int length = calculate_array_max_length(writer, array, header_size);
1360 u4 size = header_size + length * sizeof(address);
1361
1362 writer->start_sub_record(HPROF_GC_OBJ_ARRAY_DUMP, size);
1363 writer->write_objectID(array);
1364 writer->write_u4(STACK_TRACE_ID);
1365 writer->write_u4(length);
1366
1367 // array class ID
1368 writer->write_classID(array->klass());
1369
1370 // [id]* elements
1371 for (int index = 0; index < length; index++) {
1372 oop o = array->obj_at(index);
1373 if (o != nullptr && log_is_enabled(Debug, cds, heap) && mask_dormant_archived_object(o) == nullptr) {
1374 ResourceMark rm;
1375 log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s) referenced by " INTPTR_FORMAT " (%s)",
1376 p2i(o), o->klass()->external_name(),
1377 p2i(array), array->klass()->external_name());
1378 }
1379 o = mask_dormant_archived_object(o);
1380 writer->write_objectID(o);
1381 }
1382
1383 writer->end_sub_record();
1384 }
1385
1386 #define WRITE_ARRAY(Array, Type, Size, Length) \
1387 for (int i = 0; i < Length; i++) { writer->write_##Size((Size)Array->Type##_at(i)); }
1388
1389 // creates HPROF_GC_PRIM_ARRAY_DUMP record for the given type array
1390 void DumperSupport::dump_prim_array(AbstractDumpWriter* writer, typeArrayOop array) {
1391 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
1392 // 2 * sizeof(u1) + 2 * sizeof(u4) + sizeof(objectID)
1393 short header_size = 2 * 1 + 2 * 4 + sizeof(address);
1394
1395 int length = calculate_array_max_length(writer, array, header_size);
1396 int type_size = type2aelembytes(type);
1397 u4 length_in_bytes = (u4)length * type_size;
1398 u4 size = header_size + length_in_bytes;
1399
1400 writer->start_sub_record(HPROF_GC_PRIM_ARRAY_DUMP, size);
1401 writer->write_objectID(array);
1402 writer->write_u4(STACK_TRACE_ID);
1403 writer->write_u4(length);
1404 writer->write_u1(type2tag(type));
1405
1406 // nothing to copy
1407 if (length == 0) {
1408 writer->end_sub_record();
1409 return;
1410 }
1411
1412 // If the byte ordering is big endian then we can copy most types directly
1413
1414 switch (type) {
1415 case T_INT : {
1416 if (Endian::is_Java_byte_ordering_different()) {
1417 WRITE_ARRAY(array, int, u4, length);
1418 } else {
1419 writer->write_raw(array->int_at_addr(0), length_in_bytes);
1420 }
1421 break;
1422 }
1423 case T_BYTE : {
1424 writer->write_raw(array->byte_at_addr(0), length_in_bytes);
1425 break;
1426 }
1427 case T_CHAR : {
1428 if (Endian::is_Java_byte_ordering_different()) {
1429 WRITE_ARRAY(array, char, u2, length);
1430 } else {
1431 writer->write_raw(array->char_at_addr(0), length_in_bytes);
1432 }
1433 break;
1434 }
1435 case T_SHORT : {
1436 if (Endian::is_Java_byte_ordering_different()) {
1437 WRITE_ARRAY(array, short, u2, length);
1438 } else {
1439 writer->write_raw(array->short_at_addr(0), length_in_bytes);
1440 }
1441 break;
1442 }
1443 case T_BOOLEAN : {
1444 if (Endian::is_Java_byte_ordering_different()) {
1445 WRITE_ARRAY(array, bool, u1, length);
1446 } else {
1447 writer->write_raw(array->bool_at_addr(0), length_in_bytes);
1448 }
1449 break;
1450 }
1451 case T_LONG : {
1452 if (Endian::is_Java_byte_ordering_different()) {
1453 WRITE_ARRAY(array, long, u8, length);
1454 } else {
1455 writer->write_raw(array->long_at_addr(0), length_in_bytes);
1456 }
1457 break;
1458 }
1459
1460 // handle float/doubles in a special value to ensure than NaNs are
1461 // written correctly. TO DO: Check if we can avoid this on processors that
1462 // use IEEE 754.
1463
1464 case T_FLOAT : {
1465 for (int i = 0; i < length; i++) {
1466 dump_float(writer, array->float_at(i));
1467 }
1468 break;
1469 }
1470 case T_DOUBLE : {
1471 for (int i = 0; i < length; i++) {
1472 dump_double(writer, array->double_at(i));
1473 }
1474 break;
1475 }
1476 default : ShouldNotReachHere();
1477 }
1478
1479 writer->end_sub_record();
1480 }
1481
1482 // create a HPROF_FRAME record of the given Method* and bci
1483 void DumperSupport::dump_stack_frame(AbstractDumpWriter* writer,
1484 int frame_serial_num,
1485 int class_serial_num,
1486 Method* m,
1487 int bci) {
1488 int line_number;
1489 if (m->is_native()) {
1490 line_number = -3; // native frame
1491 } else {
1492 line_number = m->line_number_from_bci(bci);
1493 }
1494
1495 write_header(writer, HPROF_FRAME, 4*oopSize + 2*sizeof(u4));
1496 writer->write_id(frame_serial_num); // frame serial number
1497 writer->write_symbolID(m->name()); // method's name
1498 writer->write_symbolID(m->signature()); // method's signature
1499
1500 assert(m->method_holder()->is_instance_klass(), "not InstanceKlass");
1501 writer->write_symbolID(m->method_holder()->source_file_name()); // source file name
1502 writer->write_u4(class_serial_num); // class serial number
1503 writer->write_u4((u4) line_number); // line number
1504 }
1505
1506
1507 // Support class used to generate HPROF_UTF8 records from the entries in the
1508 // SymbolTable.
1509
1510 class SymbolTableDumper : public SymbolClosure {
1511 private:
1512 AbstractDumpWriter* _writer;
1513 AbstractDumpWriter* writer() const { return _writer; }
1514 public:
1515 SymbolTableDumper(AbstractDumpWriter* writer) { _writer = writer; }
1516 void do_symbol(Symbol** p);
1517 };
1518
1519 void SymbolTableDumper::do_symbol(Symbol** p) {
1520 ResourceMark rm;
1521 Symbol* sym = *p;
1522 int len = sym->utf8_length();
1523 if (len > 0) {
1524 char* s = sym->as_utf8();
1525 DumperSupport::write_header(writer(), HPROF_UTF8, oopSize + len);
1526 writer()->write_symbolID(sym);
1527 writer()->write_raw(s, len);
1528 }
1529 }
1530
1531 // Support class used to generate HPROF_GC_ROOT_JNI_LOCAL records
1532
1533 class JNILocalsDumper : public OopClosure {
1534 private:
1535 AbstractDumpWriter* _writer;
1536 u4 _thread_serial_num;
1537 int _frame_num;
1538 AbstractDumpWriter* writer() const { return _writer; }
1539 public:
1540 JNILocalsDumper(AbstractDumpWriter* writer, u4 thread_serial_num) {
1541 _writer = writer;
1542 _thread_serial_num = thread_serial_num;
1543 _frame_num = -1; // default - empty stack
1544 }
1545 void set_frame_number(int n) { _frame_num = n; }
1546 void do_oop(oop* obj_p);
1547 void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
1548 };
1549
1550
1551 void JNILocalsDumper::do_oop(oop* obj_p) {
1552 // ignore null handles
1553 oop o = *obj_p;
1554 if (o != nullptr) {
1555 u4 size = 1 + sizeof(address) + 4 + 4;
1556 writer()->start_sub_record(HPROF_GC_ROOT_JNI_LOCAL, size);
1557 writer()->write_objectID(o);
1558 writer()->write_u4(_thread_serial_num);
1559 writer()->write_u4((u4)_frame_num);
1560 writer()->end_sub_record();
1561 }
1562 }
1563
1564
1565 // Support class used to generate HPROF_GC_ROOT_JNI_GLOBAL records
1566
1567 class JNIGlobalsDumper : public OopClosure {
1568 private:
1569 AbstractDumpWriter* _writer;
1570 AbstractDumpWriter* writer() const { return _writer; }
1571
1572 public:
1573 JNIGlobalsDumper(AbstractDumpWriter* writer) {
1574 _writer = writer;
1575 }
1576 void do_oop(oop* obj_p);
1577 void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
1578 };
1579
1580 void JNIGlobalsDumper::do_oop(oop* obj_p) {
1581 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
1582
1583 // ignore these
1584 if (o == nullptr) return;
1585 // we ignore global ref to symbols and other internal objects
1586 if (o->is_instance() || o->is_objArray() || o->is_typeArray()) {
1587 u4 size = 1 + 2 * sizeof(address);
1588 writer()->start_sub_record(HPROF_GC_ROOT_JNI_GLOBAL, size);
1589 writer()->write_objectID(o);
1590 writer()->write_rootID(obj_p); // global ref ID
1591 writer()->end_sub_record();
1592 }
1593 };
1594
1595 // Support class used to generate HPROF_GC_ROOT_STICKY_CLASS records
1596
1597 class StickyClassDumper : public KlassClosure {
1598 private:
1599 AbstractDumpWriter* _writer;
1600 AbstractDumpWriter* writer() const { return _writer; }
1601 public:
1602 StickyClassDumper(AbstractDumpWriter* writer) {
1603 _writer = writer;
1604 }
1605 void do_klass(Klass* k) {
1606 if (k->is_instance_klass()) {
1607 InstanceKlass* ik = InstanceKlass::cast(k);
1608 u4 size = 1 + sizeof(address);
1609 writer()->start_sub_record(HPROF_GC_ROOT_STICKY_CLASS, size);
1610 writer()->write_classID(ik);
1611 writer()->end_sub_record();
1612 }
1613 }
1614 };
1615
1616 // Large object heap dump support.
1617 // To avoid memory consumption, when dumping large objects such as huge array and
1618 // large objects whose size are larger than LARGE_OBJECT_DUMP_THRESHOLD, the scanned
1619 // partial object/array data will be sent to the backend directly instead of caching
1620 // the whole object/array in the internal buffer.
1621 // The HeapDumpLargeObjectList is used to save the large object when dumper scans
1622 // the heap. The large objects could be added (push) parallelly by multiple dumpers,
1623 // But they will be removed (popped) serially only by the VM thread.
1624 class HeapDumpLargeObjectList : public CHeapObj<mtInternal> {
1625 private:
1626 class HeapDumpLargeObjectListElem : public CHeapObj<mtInternal> {
1627 public:
1628 HeapDumpLargeObjectListElem(oop obj) : _obj(obj), _next(nullptr) { }
1629 oop _obj;
1630 HeapDumpLargeObjectListElem* _next;
1631 };
1632
1633 volatile HeapDumpLargeObjectListElem* _head;
1634
1635 public:
1636 HeapDumpLargeObjectList() : _head(nullptr) { }
1637
1638 void atomic_push(oop obj) {
1639 assert (obj != nullptr, "sanity check");
1640 HeapDumpLargeObjectListElem* entry = new HeapDumpLargeObjectListElem(obj);
1641 if (entry == nullptr) {
1642 warning("failed to allocate element for large object list");
1643 return;
1644 }
1645 assert (entry->_obj != nullptr, "sanity check");
1646 while (true) {
1647 volatile HeapDumpLargeObjectListElem* old_head = Atomic::load_acquire(&_head);
1648 HeapDumpLargeObjectListElem* new_head = entry;
1649 if (Atomic::cmpxchg(&_head, old_head, new_head) == old_head) {
1650 // successfully push
1651 new_head->_next = (HeapDumpLargeObjectListElem*)old_head;
1652 return;
1653 }
1654 }
1655 }
1656
1657 oop pop() {
1658 if (_head == nullptr) {
1659 return nullptr;
1660 }
1661 HeapDumpLargeObjectListElem* entry = (HeapDumpLargeObjectListElem*)_head;
1662 _head = _head->_next;
1663 assert (entry != nullptr, "illegal larger object list entry");
1664 oop ret = entry->_obj;
1665 delete entry;
1666 assert (ret != nullptr, "illegal oop pointer");
1667 return ret;
1668 }
1669
1670 void drain(ObjectClosure* cl) {
1671 while (_head != nullptr) {
1672 cl->do_object(pop());
1673 }
1674 }
1675
1676 bool is_empty() {
1677 return _head == nullptr;
1678 }
1679
1680 static const size_t LargeObjectSizeThreshold = 1 << 20; // 1 MB
1681 };
1682
1683 class VM_HeapDumper;
1684
1685 // Support class using when iterating over the heap.
1686 class HeapObjectDumper : public ObjectClosure {
1687 private:
1688 AbstractDumpWriter* _writer;
1689 HeapDumpLargeObjectList* _list;
1690
1691 AbstractDumpWriter* writer() { return _writer; }
1692 bool is_large(oop o);
1693 public:
1694 HeapObjectDumper(AbstractDumpWriter* writer, HeapDumpLargeObjectList* list = nullptr) {
1695 _writer = writer;
1696 _list = list;
1697 }
1698
1699 // called for each object in the heap
1700 void do_object(oop o);
1701 };
1702
1703 void HeapObjectDumper::do_object(oop o) {
1704 // skip classes as these emitted as HPROF_GC_CLASS_DUMP records
1705 if (o->klass() == vmClasses::Class_klass()) {
1706 if (!java_lang_Class::is_primitive(o)) {
1707 return;
1708 }
1709 }
1710
1711 if (DumperSupport::mask_dormant_archived_object(o) == nullptr) {
1712 log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o), o->klass()->external_name());
1713 return;
1714 }
1715
1716 // If large object list exists and it is large object/array,
1717 // add oop into the list and skip scan. VM thread will process it later.
1718 if (_list != nullptr && is_large(o)) {
1719 _list->atomic_push(o);
1720 return;
1721 }
1722
1723 if (o->is_instance()) {
1724 // create a HPROF_GC_INSTANCE record for each object
1725 DumperSupport::dump_instance(writer(), o);
1726 } else if (o->is_objArray()) {
1727 // create a HPROF_GC_OBJ_ARRAY_DUMP record for each object array
1728 DumperSupport::dump_object_array(writer(), objArrayOop(o));
1729 } else if (o->is_typeArray()) {
1730 // create a HPROF_GC_PRIM_ARRAY_DUMP record for each type array
1731 DumperSupport::dump_prim_array(writer(), typeArrayOop(o));
1732 }
1733 }
1734
1735 bool HeapObjectDumper::is_large(oop o) {
1736 size_t size = 0;
1737 if (o->is_instance()) {
1738 // Use o->size() * 8 as the upper limit of instance size to avoid iterating static fields
1739 size = o->size() * 8;
1740 } else if (o->is_objArray()) {
1741 objArrayOop array = objArrayOop(o);
1742 BasicType type = ArrayKlass::cast(array->klass())->element_type();
1743 assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type");
1744 int length = array->length();
1745 int type_size = sizeof(address);
1746 size = (size_t)length * type_size;
1747 } else if (o->is_typeArray()) {
1748 typeArrayOop array = typeArrayOop(o);
1749 BasicType type = ArrayKlass::cast(array->klass())->element_type();
1750 assert(type >= T_BOOLEAN && type <= T_OBJECT, "invalid array element type");
1751 int length = array->length();
1752 int type_size = type2aelembytes(type);
1753 size = (size_t)length * type_size;
1754 }
1755 return size > HeapDumpLargeObjectList::LargeObjectSizeThreshold;
1756 }
1757
1758 // The dumper controller for parallel heap dump
1759 class DumperController : public CHeapObj<mtInternal> {
1760 private:
1761 bool _started;
1762 Monitor* _lock;
1763 uint _dumper_number;
1764 uint _complete_number;
1765
1766 public:
1767 DumperController(uint number) :
1768 _started(false),
1769 _lock(new (std::nothrow) PaddedMonitor(Mutex::safepoint, "DumperController_lock")),
1770 _dumper_number(number),
1771 _complete_number(0) { }
1772
1773 ~DumperController() { delete _lock; }
1774
1775 void wait_for_start_signal() {
1776 MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
1777 while (_started == false) {
1778 ml.wait();
1779 }
1780 assert(_started == true, "dumper woke up with wrong state");
1781 }
1782
1783 void start_dump() {
1784 assert (_started == false, "start dump with wrong state");
1785 MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
1786 _started = true;
1787 ml.notify_all();
1788 }
1789
1790 void dumper_complete() {
1791 assert (_started == true, "dumper complete with wrong state");
1792 MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
1793 _complete_number++;
1794 ml.notify();
1795 }
1796
1797 void wait_all_dumpers_complete() {
1798 assert (_started == true, "wrong state when wait for dumper complete");
1799 MonitorLocker ml(_lock, Mutex::_no_safepoint_check_flag);
1800 while (_complete_number != _dumper_number) {
1801 ml.wait();
1802 }
1803 _started = false;
1804 }
1805 };
1806
1807 // The VM operation that performs the heap dump
1808 class VM_HeapDumper : public VM_GC_Operation, public WorkerTask {
1809 private:
1810 static VM_HeapDumper* _global_dumper;
1811 static DumpWriter* _global_writer;
1812 DumpWriter* _local_writer;
1813 JavaThread* _oome_thread;
1814 Method* _oome_constructor;
1815 bool _gc_before_heap_dump;
1816 GrowableArray<Klass*>* _klass_map;
1817 ThreadStackTrace** _stack_traces;
1818 int _num_threads;
1819 // parallel heap dump support
1820 uint _num_dumper_threads;
1821 uint _num_writer_threads;
1822 DumperController* _dumper_controller;
1823 ParallelObjectIterator* _poi;
1824 HeapDumpLargeObjectList* _large_object_list;
1825
1826 // VMDumperType is for thread that dumps both heap and non-heap data.
1827 static const size_t VMDumperType = 0;
1828 static const size_t WriterType = 1;
1829 static const size_t DumperType = 2;
1830 // worker id of VMDumper thread.
1831 static const size_t VMDumperWorkerId = 0;
1832
1833 size_t get_worker_type(uint worker_id) {
1834 assert(_num_writer_threads >= 1, "Must be at least one writer");
1835 // worker id of VMDumper that dump heap and non-heap data
1836 if (worker_id == VMDumperWorkerId) {
1837 return VMDumperType;
1838 }
1839
1840 // worker id of dumper starts from 1, which only dump heap datar
1841 if (worker_id < _num_dumper_threads) {
1842 return DumperType;
1843 }
1844
1845 // worker id of writer starts from _num_dumper_threads
1846 return WriterType;
1847 }
1848
1849 void prepare_parallel_dump(uint num_total) {
1850 assert (_dumper_controller == nullptr, "dumper controller must be null");
1851 assert (num_total > 0, "active workers number must >= 1");
1852 // Dumper threads number must not be larger than active workers number.
1853 if (num_total < _num_dumper_threads) {
1854 _num_dumper_threads = num_total - 1;
1855 }
1856 // Calculate dumper and writer threads number.
1857 _num_writer_threads = num_total - _num_dumper_threads;
1858 // If dumper threads number is 1, only the VMThread works as a dumper.
1859 // If dumper threads number is equal to active workers, need at lest one worker thread as writer.
1860 if (_num_dumper_threads > 0 && _num_writer_threads == 0) {
1861 _num_writer_threads = 1;
1862 _num_dumper_threads = num_total - _num_writer_threads;
1863 }
1864 // Prepare parallel writer.
1865 if (_num_dumper_threads > 1) {
1866 ParDumpWriter::before_work();
1867 // Number of dumper threads that only iterate heap.
1868 uint _heap_only_dumper_threads = _num_dumper_threads - 1 /* VMDumper thread */;
1869 _dumper_controller = new (std::nothrow) DumperController(_heap_only_dumper_threads);
1870 }
1871 }
1872
1873 void finish_parallel_dump() {
1874 if (_num_dumper_threads > 1) {
1875 ParDumpWriter::after_work();
1876 }
1877 }
1878
1879 // accessors and setters
1880 static VM_HeapDumper* dumper() { assert(_global_dumper != nullptr, "Error"); return _global_dumper; }
1881 static DumpWriter* writer() { assert(_global_writer != nullptr, "Error"); return _global_writer; }
1882 void set_global_dumper() {
1883 assert(_global_dumper == nullptr, "Error");
1884 _global_dumper = this;
1885 }
1886 void set_global_writer() {
1887 assert(_global_writer == nullptr, "Error");
1888 _global_writer = _local_writer;
1889 }
1890 void clear_global_dumper() { _global_dumper = nullptr; }
1891 void clear_global_writer() { _global_writer = nullptr; }
1892
1893 bool skip_operation() const;
1894
1895 // writes a HPROF_LOAD_CLASS record
1896 static void do_load_class(Klass* k);
1897
1898 // writes a HPROF_GC_CLASS_DUMP record for the given class
1899 static void do_class_dump(Klass* k);
1900
1901 // HPROF_GC_ROOT_THREAD_OBJ records
1902 int do_thread(JavaThread* thread, u4 thread_serial_num);
1903 void do_threads();
1904
1905 void add_class_serial_number(Klass* k, int serial_num) {
1906 _klass_map->at_put_grow(serial_num, k);
1907 }
1908
1909 // HPROF_TRACE and HPROF_FRAME records
1910 void dump_stack_traces();
1911
1912 // large objects
1913 void dump_large_objects(ObjectClosure* writer);
1914
1915 public:
1916 VM_HeapDumper(DumpWriter* writer, bool gc_before_heap_dump, bool oome, uint num_dump_threads) :
1917 VM_GC_Operation(0 /* total collections, dummy, ignored */,
1918 GCCause::_heap_dump /* GC Cause */,
1919 0 /* total full collections, dummy, ignored */,
1920 gc_before_heap_dump),
1921 WorkerTask("dump heap") {
1922 _local_writer = writer;
1923 _gc_before_heap_dump = gc_before_heap_dump;
1924 _klass_map = new (mtServiceability) GrowableArray<Klass*>(INITIAL_CLASS_COUNT, mtServiceability);
1925 _stack_traces = nullptr;
1926 _num_threads = 0;
1927 _num_dumper_threads = num_dump_threads;
1928 _dumper_controller = nullptr;
1929 _poi = nullptr;
1930 _large_object_list = new (std::nothrow) HeapDumpLargeObjectList();
1931 if (oome) {
1932 assert(!Thread::current()->is_VM_thread(), "Dump from OutOfMemoryError cannot be called by the VMThread");
1933 // get OutOfMemoryError zero-parameter constructor
1934 InstanceKlass* oome_ik = vmClasses::OutOfMemoryError_klass();
1935 _oome_constructor = oome_ik->find_method(vmSymbols::object_initializer_name(),
1936 vmSymbols::void_method_signature());
1937 // get thread throwing OOME when generating the heap dump at OOME
1938 _oome_thread = JavaThread::current();
1939 } else {
1940 _oome_thread = nullptr;
1941 _oome_constructor = nullptr;
1942 }
1943 }
1944
1945 ~VM_HeapDumper() {
1946 if (_stack_traces != nullptr) {
1947 for (int i=0; i < _num_threads; i++) {
1948 delete _stack_traces[i];
1949 }
1950 FREE_C_HEAP_ARRAY(ThreadStackTrace*, _stack_traces);
1951 }
1952 if (_dumper_controller != nullptr) {
1953 delete _dumper_controller;
1954 _dumper_controller = nullptr;
1955 }
1956 delete _klass_map;
1957 delete _large_object_list;
1958 }
1959
1960 VMOp_Type type() const { return VMOp_HeapDumper; }
1961 virtual bool doit_prologue();
1962 void doit();
1963 void work(uint worker_id);
1964 };
1965
1966 VM_HeapDumper* VM_HeapDumper::_global_dumper = nullptr;
1967 DumpWriter* VM_HeapDumper::_global_writer = nullptr;
1968
1969 bool VM_HeapDumper::skip_operation() const {
1970 return false;
1971 }
1972
1973 // fixes up the current dump record and writes HPROF_HEAP_DUMP_END record
1974 void DumperSupport::end_of_dump(AbstractDumpWriter* writer) {
1975 writer->finish_dump_segment();
1976
1977 writer->write_u1(HPROF_HEAP_DUMP_END);
1978 writer->write_u4(0);
1979 writer->write_u4(0);
1980 }
1981
1982 // writes a HPROF_LOAD_CLASS record for the class
1983 void VM_HeapDumper::do_load_class(Klass* k) {
1984 static u4 class_serial_num = 0;
1985
1986 // len of HPROF_LOAD_CLASS record
1987 u4 remaining = 2*oopSize + 2*sizeof(u4);
1988
1989 DumperSupport::write_header(writer(), HPROF_LOAD_CLASS, remaining);
1990
1991 // class serial number is just a number
1992 writer()->write_u4(++class_serial_num);
1993
1994 // class ID
1995 writer()->write_classID(k);
1996
1997 // add the Klass* and class serial number pair
1998 dumper()->add_class_serial_number(k, class_serial_num);
1999
2000 writer()->write_u4(STACK_TRACE_ID);
2001
2002 // class name ID
2003 Symbol* name = k->name();
2004 writer()->write_symbolID(name);
2005 }
2006
2007 // writes a HPROF_GC_CLASS_DUMP record for the given class
2008 void VM_HeapDumper::do_class_dump(Klass* k) {
2009 if (k->is_instance_klass()) {
2010 DumperSupport::dump_instance_class(writer(), k);
2011 } else {
2012 DumperSupport::dump_array_class(writer(), k);
2013 }
2014 }
2015
2016 // Walk the stack of the given thread.
2017 // Dumps a HPROF_GC_ROOT_JAVA_FRAME record for each local
2018 // Dumps a HPROF_GC_ROOT_JNI_LOCAL record for each JNI local
2019 //
2020 // It returns the number of Java frames in this thread stack
2021 int VM_HeapDumper::do_thread(JavaThread* java_thread, u4 thread_serial_num) {
2022 JNILocalsDumper blk(writer(), thread_serial_num);
2023
2024 oop threadObj = java_thread->threadObj();
2025 assert(threadObj != nullptr, "sanity check");
2026
2027 int stack_depth = 0;
2028 if (java_thread->has_last_Java_frame()) {
2029
2030 // vframes are resource allocated
2031 Thread* current_thread = Thread::current();
2032 ResourceMark rm(current_thread);
2033 HandleMark hm(current_thread);
2034
2035 RegisterMap reg_map(java_thread,
2036 RegisterMap::UpdateMap::include,
2037 RegisterMap::ProcessFrames::include,
2038 RegisterMap::WalkContinuation::skip);
2039 frame f = java_thread->last_frame();
2040 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
2041 frame* last_entry_frame = nullptr;
2042 int extra_frames = 0;
2043
2044 if (java_thread == _oome_thread && _oome_constructor != nullptr) {
2045 extra_frames++;
2046 }
2047 while (vf != nullptr) {
2048 blk.set_frame_number(stack_depth);
2049 if (vf->is_java_frame()) {
2050
2051 // java frame (interpreted, compiled, ...)
2052 javaVFrame *jvf = javaVFrame::cast(vf);
2053 if (!(jvf->method()->is_native())) {
2054 StackValueCollection* locals = jvf->locals();
2055 for (int slot=0; slot<locals->size(); slot++) {
2056 if (locals->at(slot)->type() == T_OBJECT) {
2057 oop o = locals->obj_at(slot)();
2058
2059 if (o != nullptr) {
2060 u4 size = 1 + sizeof(address) + 4 + 4;
2061 writer()->start_sub_record(HPROF_GC_ROOT_JAVA_FRAME, size);
2062 writer()->write_objectID(o);
2063 writer()->write_u4(thread_serial_num);
2064 writer()->write_u4((u4) (stack_depth + extra_frames));
2065 writer()->end_sub_record();
2066 }
2067 }
2068 }
2069 StackValueCollection *exprs = jvf->expressions();
2070 for(int index = 0; index < exprs->size(); index++) {
2071 if (exprs->at(index)->type() == T_OBJECT) {
2072 oop o = exprs->obj_at(index)();
2073 if (o != nullptr) {
2074 u4 size = 1 + sizeof(address) + 4 + 4;
2075 writer()->start_sub_record(HPROF_GC_ROOT_JAVA_FRAME, size);
2076 writer()->write_objectID(o);
2077 writer()->write_u4(thread_serial_num);
2078 writer()->write_u4((u4) (stack_depth + extra_frames));
2079 writer()->end_sub_record();
2080 }
2081 }
2082 }
2083 } else {
2084 // native frame
2085 if (stack_depth == 0) {
2086 // JNI locals for the top frame.
2087 java_thread->active_handles()->oops_do(&blk);
2088 } else {
2089 if (last_entry_frame != nullptr) {
2090 // JNI locals for the entry frame
2091 assert(last_entry_frame->is_entry_frame(), "checking");
2092 last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(&blk);
2093 }
2094 }
2095 }
2096 // increment only for Java frames
2097 stack_depth++;
2098 last_entry_frame = nullptr;
2099
2100 } else {
2101 // externalVFrame - if it's an entry frame then report any JNI locals
2102 // as roots when we find the corresponding native javaVFrame
2103 frame* fr = vf->frame_pointer();
2104 assert(fr != nullptr, "sanity check");
2105 if (fr->is_entry_frame()) {
2106 last_entry_frame = fr;
2107 }
2108 }
2109 vf = vf->sender();
2110 }
2111 } else {
2112 // no last java frame but there may be JNI locals
2113 java_thread->active_handles()->oops_do(&blk);
2114 }
2115 return stack_depth;
2116 }
2117
2118
2119 // write a HPROF_GC_ROOT_THREAD_OBJ record for each java thread. Then walk
2120 // the stack so that locals and JNI locals are dumped.
2121 void VM_HeapDumper::do_threads() {
2122 for (int i=0; i < _num_threads; i++) {
2123 JavaThread* thread = _stack_traces[i]->thread();
2124 oop threadObj = thread->threadObj();
2125 u4 thread_serial_num = i+1;
2126 u4 stack_serial_num = thread_serial_num + STACK_TRACE_ID;
2127 u4 size = 1 + sizeof(address) + 4 + 4;
2128 writer()->start_sub_record(HPROF_GC_ROOT_THREAD_OBJ, size);
2129 writer()->write_objectID(threadObj);
2130 writer()->write_u4(thread_serial_num); // thread number
2131 writer()->write_u4(stack_serial_num); // stack trace serial number
2132 writer()->end_sub_record();
2133 int num_frames = do_thread(thread, thread_serial_num);
2134 assert(num_frames == _stack_traces[i]->get_stack_depth(),
2135 "total number of Java frames not matched");
2136 }
2137 }
2138
2139 bool VM_HeapDumper::doit_prologue() {
2140 if (_gc_before_heap_dump && UseZGC) {
2141 // ZGC cannot perform a synchronous GC cycle from within the VM thread.
2142 // So ZCollectedHeap::collect_as_vm_thread() is a noop. To respect the
2143 // _gc_before_heap_dump flag a synchronous GC cycle is performed from
2144 // the caller thread in the prologue.
2145 Universe::heap()->collect(GCCause::_heap_dump);
2146 }
2147 return VM_GC_Operation::doit_prologue();
2148 }
2149
2150
2151 // The VM operation that dumps the heap. The dump consists of the following
2152 // records:
2153 //
2154 // HPROF_HEADER
2155 // [HPROF_UTF8]*
2156 // [HPROF_LOAD_CLASS]*
2157 // [[HPROF_FRAME]*|HPROF_TRACE]*
2158 // [HPROF_GC_CLASS_DUMP]*
2159 // [HPROF_HEAP_DUMP_SEGMENT]*
2160 // HPROF_HEAP_DUMP_END
2161 //
2162 // The HPROF_TRACE records represent the stack traces where the heap dump
2163 // is generated and a "dummy trace" record which does not include
2164 // any frames. The dummy trace record is used to be referenced as the
2165 // unknown object alloc site.
2166 //
2167 // Each HPROF_HEAP_DUMP_SEGMENT record has a length followed by sub-records.
2168 // To allow the heap dump be generated in a single pass we remember the position
2169 // of the dump length and fix it up after all sub-records have been written.
2170 // To generate the sub-records we iterate over the heap, writing
2171 // HPROF_GC_INSTANCE_DUMP, HPROF_GC_OBJ_ARRAY_DUMP, and HPROF_GC_PRIM_ARRAY_DUMP
2172 // records as we go. Once that is done we write records for some of the GC
2173 // roots.
2174
2175 void VM_HeapDumper::doit() {
2176
2177 CollectedHeap* ch = Universe::heap();
2178
2179 ch->ensure_parsability(false); // must happen, even if collection does
2180 // not happen (e.g. due to GCLocker)
2181
2182 if (_gc_before_heap_dump) {
2183 if (GCLocker::is_active()) {
2184 warning("GC locker is held; pre-heapdump GC was skipped");
2185 } else {
2186 ch->collect_as_vm_thread(GCCause::_heap_dump);
2187 }
2188 }
2189
2190 // At this point we should be the only dumper active, so
2191 // the following should be safe.
2192 set_global_dumper();
2193 set_global_writer();
2194
2195 WorkerThreads* workers = ch->safepoint_workers();
2196
2197 if (workers == nullptr) {
2198 // Use serial dump, set dumper threads and writer threads number to 1.
2199 _num_dumper_threads=1;
2200 _num_writer_threads=1;
2201 work(0);
2202 } else {
2203 prepare_parallel_dump(workers->active_workers());
2204 if (_num_dumper_threads > 1) {
2205 ParallelObjectIterator poi(_num_dumper_threads);
2206 _poi = &poi;
2207 workers->run_task(this);
2208 _poi = nullptr;
2209 } else {
2210 workers->run_task(this);
2211 }
2212 finish_parallel_dump();
2213 }
2214
2215 // Now we clear the global variables, so that a future dumper can run.
2216 clear_global_dumper();
2217 clear_global_writer();
2218 }
2219
2220 void VM_HeapDumper::work(uint worker_id) {
2221 if (worker_id != 0) {
2222 if (get_worker_type(worker_id) == WriterType) {
2223 writer()->writer_loop();
2224 return;
2225 }
2226 if (_num_dumper_threads > 1 && get_worker_type(worker_id) == DumperType) {
2227 _dumper_controller->wait_for_start_signal();
2228 }
2229 } else {
2230 // The worker 0 on all non-heap data dumping and part of heap iteration.
2231 // Write the file header - we always use 1.0.2
2232 const char* header = "JAVA PROFILE 1.0.2";
2233
2234 // header is few bytes long - no chance to overflow int
2235 writer()->write_raw(header, strlen(header) + 1); // NUL terminated
2236 writer()->write_u4(oopSize);
2237 // timestamp is current time in ms
2238 writer()->write_u8(os::javaTimeMillis());
2239 // HPROF_UTF8 records
2240 SymbolTableDumper sym_dumper(writer());
2241 SymbolTable::symbols_do(&sym_dumper);
2242
2243 // write HPROF_LOAD_CLASS records
2244 {
2245 LockedClassesDo locked_load_classes(&do_load_class);
2246 ClassLoaderDataGraph::classes_do(&locked_load_classes);
2247 }
2248
2249 // write HPROF_FRAME and HPROF_TRACE records
2250 // this must be called after _klass_map is built when iterating the classes above.
2251 dump_stack_traces();
2252
2253 // Writes HPROF_GC_CLASS_DUMP records
2254 {
2255 LockedClassesDo locked_dump_class(&do_class_dump);
2256 ClassLoaderDataGraph::classes_do(&locked_dump_class);
2257 }
2258
2259 // HPROF_GC_ROOT_THREAD_OBJ + frames + jni locals
2260 do_threads();
2261
2262 // HPROF_GC_ROOT_JNI_GLOBAL
2263 JNIGlobalsDumper jni_dumper(writer());
2264 JNIHandles::oops_do(&jni_dumper);
2265 // technically not jni roots, but global roots
2266 // for things like preallocated throwable backtraces
2267 Universe::vm_global()->oops_do(&jni_dumper);
2268 // HPROF_GC_ROOT_STICKY_CLASS
2269 // These should be classes in the null class loader data, and not all classes
2270 // if !ClassUnloading
2271 StickyClassDumper class_dumper(writer());
2272 ClassLoaderData::the_null_class_loader_data()->classes_do(&class_dumper);
2273 }
2274 // writes HPROF_GC_INSTANCE_DUMP records.
2275 // After each sub-record is written check_segment_length will be invoked
2276 // to check if the current segment exceeds a threshold. If so, a new
2277 // segment is started.
2278 // The HPROF_GC_CLASS_DUMP and HPROF_GC_INSTANCE_DUMP are the vast bulk
2279 // of the heap dump.
2280 if (_num_dumper_threads <= 1) {
2281 HeapObjectDumper obj_dumper(writer());
2282 Universe::heap()->object_iterate(&obj_dumper);
2283 } else {
2284 assert(get_worker_type(worker_id) == DumperType
2285 || get_worker_type(worker_id) == VMDumperType,
2286 "must be dumper thread to do heap iteration");
2287 if (get_worker_type(worker_id) == VMDumperType) {
2288 // Clear global writer's buffer.
2289 writer()->finish_dump_segment(true);
2290 // Notify dumpers to start heap iteration.
2291 _dumper_controller->start_dump();
2292 }
2293 // Heap iteration.
2294 {
2295 ParDumpWriter pw(writer());
2296 {
2297 HeapObjectDumper obj_dumper(&pw, _large_object_list);
2298 _poi->object_iterate(&obj_dumper, worker_id);
2299 }
2300
2301 if (get_worker_type(worker_id) == VMDumperType) {
2302 _dumper_controller->wait_all_dumpers_complete();
2303 // clear internal buffer;
2304 pw.finish_dump_segment(true);
2305 // refresh the global_writer's buffer and position;
2306 writer()->refresh();
2307 } else {
2308 pw.finish_dump_segment(true);
2309 _dumper_controller->dumper_complete();
2310 return;
2311 }
2312 }
2313 }
2314
2315 assert(get_worker_type(worker_id) == VMDumperType, "Heap dumper must be VMDumper");
2316 // Use writer() rather than ParDumpWriter to avoid memory consumption.
2317 HeapObjectDumper obj_dumper(writer());
2318 dump_large_objects(&obj_dumper);
2319 // Writes the HPROF_HEAP_DUMP_END record.
2320 DumperSupport::end_of_dump(writer());
2321 // We are done with writing. Release the worker threads.
2322 writer()->deactivate();
2323 }
2324
2325 void VM_HeapDumper::dump_stack_traces() {
2326 // write a HPROF_TRACE record without any frames to be referenced as object alloc sites
2327 DumperSupport::write_header(writer(), HPROF_TRACE, 3*sizeof(u4));
2328 writer()->write_u4((u4) STACK_TRACE_ID);
2329 writer()->write_u4(0); // thread number
2330 writer()->write_u4(0); // frame count
2331
2332 _stack_traces = NEW_C_HEAP_ARRAY(ThreadStackTrace*, Threads::number_of_threads(), mtInternal);
2333 int frame_serial_num = 0;
2334 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
2335 oop threadObj = thread->threadObj();
2336 if (threadObj != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
2337 // dump thread stack trace
2338 Thread* current_thread = Thread::current();
2339 ResourceMark rm(current_thread);
2340 HandleMark hm(current_thread);
2341
2342 ThreadStackTrace* stack_trace = new ThreadStackTrace(thread, false);
2343 stack_trace->dump_stack_at_safepoint(-1, /* ObjectMonitorsHashtable is not needed here */ nullptr, true);
2344 _stack_traces[_num_threads++] = stack_trace;
2345
2346 // write HPROF_FRAME records for this thread's stack trace
2347 int depth = stack_trace->get_stack_depth();
2348 int thread_frame_start = frame_serial_num;
2349 int extra_frames = 0;
2350 // write fake frame that makes it look like the thread, which caused OOME,
2351 // is in the OutOfMemoryError zero-parameter constructor
2352 if (thread == _oome_thread && _oome_constructor != nullptr) {
2353 int oome_serial_num = _klass_map->find(_oome_constructor->method_holder());
2354 // the class serial number starts from 1
2355 assert(oome_serial_num > 0, "OutOfMemoryError class not found");
2356 DumperSupport::dump_stack_frame(writer(), ++frame_serial_num, oome_serial_num,
2357 _oome_constructor, 0);
2358 extra_frames++;
2359 }
2360 for (int j=0; j < depth; j++) {
2361 StackFrameInfo* frame = stack_trace->stack_frame_at(j);
2362 Method* m = frame->method();
2363 int class_serial_num = _klass_map->find(m->method_holder());
2364 // the class serial number starts from 1
2365 assert(class_serial_num > 0, "class not found");
2366 DumperSupport::dump_stack_frame(writer(), ++frame_serial_num, class_serial_num, m, frame->bci());
2367 }
2368 depth += extra_frames;
2369
2370 // write HPROF_TRACE record for one thread
2371 DumperSupport::write_header(writer(), HPROF_TRACE, 3*sizeof(u4) + depth*oopSize);
2372 int stack_serial_num = _num_threads + STACK_TRACE_ID;
2373 writer()->write_u4(stack_serial_num); // stack trace serial number
2374 writer()->write_u4((u4) _num_threads); // thread serial number
2375 writer()->write_u4(depth); // frame count
2376 for (int j=1; j <= depth; j++) {
2377 writer()->write_id(thread_frame_start + j);
2378 }
2379 }
2380 }
2381 }
2382
2383 // dump the large objects.
2384 void VM_HeapDumper::dump_large_objects(ObjectClosure* cl) {
2385 _large_object_list->drain(cl);
2386 }
2387
2388 // dump the heap to given path.
2389 int HeapDumper::dump(const char* path, outputStream* out, int compression, bool overwrite, uint num_dump_threads) {
2390 assert(path != nullptr && strlen(path) > 0, "path missing");
2391
2392 // print message in interactive case
2393 if (out != nullptr) {
2394 out->print_cr("Dumping heap to %s ...", path);
2395 timer()->start();
2396 }
2397 // create JFR event
2398 EventHeapDump event;
2399
2400 AbstractCompressor* compressor = nullptr;
2401
2402 if (compression > 0) {
2403 compressor = new (std::nothrow) GZipCompressor(compression);
2404
2405 if (compressor == nullptr) {
2406 set_error("Could not allocate gzip compressor");
2407 return -1;
2408 }
2409 }
2410
2411 DumpWriter writer(new (std::nothrow) FileWriter(path, overwrite), compressor);
2412
2413 if (writer.error() != nullptr) {
2414 set_error(writer.error());
2415 if (out != nullptr) {
2416 out->print_cr("Unable to create %s: %s", path,
2417 (error() != nullptr) ? error() : "reason unknown");
2418 }
2419 return -1;
2420 }
2421
2422 // generate the dump
2423 VM_HeapDumper dumper(&writer, _gc_before_heap_dump, _oome, num_dump_threads);
2424 if (Thread::current()->is_VM_thread()) {
2425 assert(SafepointSynchronize::is_at_safepoint(), "Expected to be called at a safepoint");
2426 dumper.doit();
2427 } else {
2428 VMThread::execute(&dumper);
2429 }
2430
2431 // record any error that the writer may have encountered
2432 set_error(writer.error());
2433
2434 // emit JFR event
2435 if (error() == nullptr) {
2436 event.set_destination(path);
2437 event.set_gcBeforeDump(_gc_before_heap_dump);
2438 event.set_size(writer.bytes_written());
2439 event.set_onOutOfMemoryError(_oome);
2440 event.set_overwrite(overwrite);
2441 event.set_compression(compression);
2442 event.commit();
2443 } else {
2444 log_debug(cds, heap)("Error %s while dumping heap", error());
2445 }
2446
2447 // print message in interactive case
2448 if (out != nullptr) {
2449 timer()->stop();
2450 if (error() == nullptr) {
2451 out->print_cr("Heap dump file created [" JULONG_FORMAT " bytes in %3.3f secs]",
2452 writer.bytes_written(), timer()->seconds());
2453 } else {
2454 out->print_cr("Dump file is incomplete: %s", writer.error());
2455 }
2456 }
2457
2458 return (writer.error() == nullptr) ? 0 : -1;
2459 }
2460
2461 // stop timer (if still active), and free any error string we might be holding
2462 HeapDumper::~HeapDumper() {
2463 if (timer()->is_active()) {
2464 timer()->stop();
2465 }
2466 set_error(nullptr);
2467 }
2468
2469
2470 // returns the error string (resource allocated), or null
2471 char* HeapDumper::error_as_C_string() const {
2472 if (error() != nullptr) {
2473 char* str = NEW_RESOURCE_ARRAY(char, strlen(error())+1);
2474 strcpy(str, error());
2475 return str;
2476 } else {
2477 return nullptr;
2478 }
2479 }
2480
2481 // set the error string
2482 void HeapDumper::set_error(char const* error) {
2483 if (_error != nullptr) {
2484 os::free(_error);
2485 }
2486 if (error == nullptr) {
2487 _error = nullptr;
2488 } else {
2489 _error = os::strdup(error);
2490 assert(_error != nullptr, "allocation failure");
2491 }
2492 }
2493
2494 // Called by out-of-memory error reporting by a single Java thread
2495 // outside of a JVM safepoint
2496 void HeapDumper::dump_heap_from_oome() {
2497 HeapDumper::dump_heap(true);
2498 }
2499
2500 // Called by error reporting by a single Java thread outside of a JVM safepoint,
2501 // or by heap dumping by the VM thread during a (GC) safepoint. Thus, these various
2502 // callers are strictly serialized and guaranteed not to interfere below. For more
2503 // general use, however, this method will need modification to prevent
2504 // inteference when updating the static variables base_path and dump_file_seq below.
2505 void HeapDumper::dump_heap() {
2506 HeapDumper::dump_heap(false);
2507 }
2508
2509 void HeapDumper::dump_heap(bool oome) {
2510 static char base_path[JVM_MAXPATHLEN] = {'\0'};
2511 static uint dump_file_seq = 0;
2512 char* my_path;
2513 const int max_digit_chars = 20;
2514
2515 const char* dump_file_name = "java_pid";
2516 const char* dump_file_ext = HeapDumpGzipLevel > 0 ? ".hprof.gz" : ".hprof";
2517
2518 // The dump file defaults to java_pid<pid>.hprof in the current working
2519 // directory. HeapDumpPath=<file> can be used to specify an alternative
2520 // dump file name or a directory where dump file is created.
2521 if (dump_file_seq == 0) { // first time in, we initialize base_path
2522 // Calculate potentially longest base path and check if we have enough
2523 // allocated statically.
2524 const size_t total_length =
2525 (HeapDumpPath == nullptr ? 0 : strlen(HeapDumpPath)) +
2526 strlen(os::file_separator()) + max_digit_chars +
2527 strlen(dump_file_name) + strlen(dump_file_ext) + 1;
2528 if (total_length > sizeof(base_path)) {
2529 warning("Cannot create heap dump file. HeapDumpPath is too long.");
2530 return;
2531 }
2532
2533 bool use_default_filename = true;
2534 if (HeapDumpPath == nullptr || HeapDumpPath[0] == '\0') {
2535 // HeapDumpPath=<file> not specified
2536 } else {
2537 strcpy(base_path, HeapDumpPath);
2538 // check if the path is a directory (must exist)
2539 DIR* dir = os::opendir(base_path);
2540 if (dir == nullptr) {
2541 use_default_filename = false;
2542 } else {
2543 // HeapDumpPath specified a directory. We append a file separator
2544 // (if needed).
2545 os::closedir(dir);
2546 size_t fs_len = strlen(os::file_separator());
2547 if (strlen(base_path) >= fs_len) {
2548 char* end = base_path;
2549 end += (strlen(base_path) - fs_len);
2550 if (strcmp(end, os::file_separator()) != 0) {
2551 strcat(base_path, os::file_separator());
2552 }
2553 }
2554 }
2555 }
2556 // If HeapDumpPath wasn't a file name then we append the default name
2557 if (use_default_filename) {
2558 const size_t dlen = strlen(base_path); // if heap dump dir specified
2559 jio_snprintf(&base_path[dlen], sizeof(base_path)-dlen, "%s%d%s",
2560 dump_file_name, os::current_process_id(), dump_file_ext);
2561 }
2562 const size_t len = strlen(base_path) + 1;
2563 my_path = (char*)os::malloc(len, mtInternal);
2564 if (my_path == nullptr) {
2565 warning("Cannot create heap dump file. Out of system memory.");
2566 return;
2567 }
2568 strncpy(my_path, base_path, len);
2569 } else {
2570 // Append a sequence number id for dumps following the first
2571 const size_t len = strlen(base_path) + max_digit_chars + 2; // for '.' and \0
2572 my_path = (char*)os::malloc(len, mtInternal);
2573 if (my_path == nullptr) {
2574 warning("Cannot create heap dump file. Out of system memory.");
2575 return;
2576 }
2577 jio_snprintf(my_path, len, "%s.%d", base_path, dump_file_seq);
2578 }
2579 dump_file_seq++; // increment seq number for next time we dump
2580
2581 HeapDumper dumper(false /* no GC before heap dump */,
2582 oome /* pass along out-of-memory-error flag */);
2583 dumper.dump(my_path, tty, HeapDumpGzipLevel);
2584 os::free(my_path);
2585 }