1 /*
2 * Copyright (c) 2019, 2021, 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 "gc/shared/collectedHeap.hpp"
27 #include "gc/shared/gc_globals.hpp"
28 #include "jfr/leakprofiler/leakProfiler.hpp"
29 #include "jfr/leakprofiler/chains/bfsClosure.hpp"
30 #include "jfr/leakprofiler/chains/dfsClosure.hpp"
31 #include "jfr/leakprofiler/chains/edge.hpp"
32 #include "jfr/leakprofiler/chains/edgeQueue.hpp"
33 #include "jfr/leakprofiler/chains/edgeStore.hpp"
34 #include "jfr/leakprofiler/chains/jfrbitset.hpp"
35 #include "jfr/leakprofiler/chains/objectSampleMarker.hpp"
36 #include "jfr/leakprofiler/chains/rootSetClosure.hpp"
37 #include "jfr/leakprofiler/chains/edgeStore.hpp"
38 #include "jfr/leakprofiler/chains/objectSampleMarker.hpp"
39 #include "jfr/leakprofiler/chains/pathToGcRootsOperation.hpp"
40 #include "jfr/leakprofiler/checkpoint/eventEmitter.hpp"
41 #include "jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp"
42 #include "jfr/leakprofiler/sampling/objectSample.hpp"
43 #include "jfr/leakprofiler/sampling/objectSampler.hpp"
44 #include "jfr/leakprofiler/utilities/granularTimer.hpp"
45 #include "logging/log.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/oop.inline.hpp"
48 #include "runtime/safepoint.hpp"
49 #include "utilities/globalDefinitions.hpp"
50
51 PathToGcRootsOperation::PathToGcRootsOperation(ObjectSampler* sampler, EdgeStore* edge_store, int64_t cutoff, bool emit_all, bool skip_bfs) :
52 _sampler(sampler),_edge_store(edge_store), _cutoff_ticks(cutoff), _emit_all(emit_all), _skip_bfs(skip_bfs) {}
53
54 /* The EdgeQueue is backed by directly managed virtual memory.
55 * We will attempt to dimension an initial reservation
56 * in proportion to the size of the heap (represented by heap_region).
57 * Initial memory reservation: 5% of the heap OR at least 32 Mb
58 * Commit ratio: 1 : 10 (subject to allocation granularties)
59 */
60 static size_t edge_queue_memory_reservation() {
61 const size_t memory_reservation_bytes = MAX2(MaxHeapSize / 20, 32*M);
62 assert(memory_reservation_bytes >= (size_t)32*M, "invariant");
63 return memory_reservation_bytes;
64 }
65
66 static size_t edge_queue_memory_commit_size(size_t memory_reservation_bytes) {
67 const size_t memory_commit_block_size_bytes = memory_reservation_bytes / 10;
68 assert(memory_commit_block_size_bytes >= (size_t)3*M, "invariant");
69 return memory_commit_block_size_bytes;
70 }
71
72 static void log_edge_queue_summary(const EdgeQueue& edge_queue) {
73 log_trace(jfr, system)("EdgeQueue reserved size total: " SIZE_FORMAT " [KB]", edge_queue.reserved_size() / K);
74 log_trace(jfr, system)("EdgeQueue edges total: " SIZE_FORMAT, edge_queue.top());
75 log_trace(jfr, system)("EdgeQueue liveset total: " SIZE_FORMAT " [KB]", edge_queue.live_set() / K);
76 if (edge_queue.reserved_size() > 0) {
77 log_trace(jfr, system)("EdgeQueue commit reserve ratio: %f\n",
78 ((double)edge_queue.live_set() / (double)edge_queue.reserved_size()));
79 }
80 }
81
82 void PathToGcRootsOperation::doit() {
83 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
84 assert(_cutoff_ticks > 0, "invariant");
85
86 // The bitset used for marking is dimensioned as a function of the heap size
87 JFRBitSet mark_bits;
88
89 // The edge queue is dimensioned as a fraction of the heap size
90 const size_t edge_queue_reservation_size = edge_queue_memory_reservation();
91 EdgeQueue edge_queue(edge_queue_reservation_size, edge_queue_memory_commit_size(edge_queue_reservation_size));
92
93 // The initialize() routines will attempt to reserve and allocate backing storage memory.
94 // Failure to accommodate will render root chain processing impossible.
95 // As a fallback on failure, just write out the existing samples, flat, without chains.
96 if (!edge_queue.initialize()) {
97 log_warning(jfr)("Unable to allocate memory for root chain processing");
98 return;
99 }
100
101 // Save the original markWord for the potential leak objects,
102 // to be restored on function exit
103 ObjectSampleMarker marker;
104 if (ObjectSampleCheckpoint::save_mark_words(_sampler, marker, _emit_all) == 0) {
105 // no valid samples to process
106 return;
107 }
108
109 // Necessary condition for attempting a root set iteration
110 Universe::heap()->ensure_parsability(false);
111
112 BFSClosure bfs(&edge_queue, _edge_store, &mark_bits);
113 RootSetClosure<BFSClosure> roots(&bfs);
114
115 GranularTimer::start(_cutoff_ticks, 1000000);
116 roots.process();
117 if (edge_queue.is_full() || _skip_bfs) {
118 // Pathological case where roots don't fit in queue
119 // Do a depth-first search, but mark roots first
120 // to avoid walking sideways over roots
121 DFSClosure::find_leaks_from_root_set(_edge_store, &mark_bits);
122 } else {
123 bfs.process();
124 }
125 GranularTimer::stop();
126 log_edge_queue_summary(edge_queue);
127
128 // Emit old objects including their reference chains as events
129 EventEmitter emitter(GranularTimer::start_time(), GranularTimer::end_time());
130 emitter.write_events(_sampler, _edge_store, _emit_all);
131 }