1 /*
2 * Copyright (c) 2019, 2020, 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 "jfr/jfrEvents.hpp"
27 #include "jfr/leakprofiler/chains/edgeStore.hpp"
28 #include "jfr/leakprofiler/chains/pathToGcRootsOperation.hpp"
29 #include "jfr/leakprofiler/checkpoint/eventEmitter.hpp"
30 #include "jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp"
31 #include "jfr/leakprofiler/sampling/objectSample.hpp"
32 #include "jfr/leakprofiler/sampling/objectSampler.hpp"
33 #include "jfr/leakprofiler/utilities/unifiedOopRef.inline.hpp"
34 #include "logging/log.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "oops/markWord.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "runtime/thread.inline.hpp"
40 #include "runtime/vmThread.hpp"
41
42 EventEmitter::EventEmitter(const JfrTicks& start_time, const JfrTicks& end_time) :
43 _start_time(start_time),
44 _end_time(end_time),
45 _thread(Thread::current()),
46 _jfr_thread_local(_thread->jfr_thread_local()),
47 _thread_id(_thread->jfr_thread_local()->thread_id()) {}
48
49 EventEmitter::~EventEmitter() {
50 // restore / reset thread local stack trace and thread id
51 _jfr_thread_local->set_thread_id(_thread_id);
52 _jfr_thread_local->clear_cached_stack_trace();
53 }
54
55 void EventEmitter::emit(ObjectSampler* sampler, int64_t cutoff_ticks, bool emit_all) {
56 assert(sampler != NULL, "invariant");
57 ResourceMark rm;
58 EdgeStore edge_store;
59 if (cutoff_ticks <= 0) {
60 // no reference chains
61 MutexLocker lock(JfrStream_lock, Mutex::_no_safepoint_check_flag);
62 // The lock is needed here to prevent the recorder thread (running flush())
63 // from writing old object events out from the thread local buffer
64 // before the required constant pools have been serialized.
65 JfrTicks time_stamp = JfrTicks::now();
66 EventEmitter emitter(time_stamp, time_stamp);
67 emitter.write_events(sampler, &edge_store, emit_all);
68 return;
69 }
70 // events emitted with reference chains require a safepoint operation
71 PathToGcRootsOperation op(sampler, &edge_store, cutoff_ticks, emit_all);
72 VMThread::execute(&op);
73 }
74
75 size_t EventEmitter::write_events(ObjectSampler* object_sampler, EdgeStore* edge_store, bool emit_all) {
76 assert_locked_or_safepoint(JfrStream_lock);
77 assert(_thread == Thread::current(), "invariant");
78 assert(_thread->jfr_thread_local() == _jfr_thread_local, "invariant");
79 assert(object_sampler != NULL, "invariant");
80 assert(edge_store != NULL, "invariant");
81
82 const jlong last_sweep = emit_all ? max_jlong : object_sampler->last_sweep().value();
83 size_t count = 0;
84
85 const ObjectSample* current = object_sampler->first();
86 while (current != NULL) {
87 ObjectSample* prev = current->prev();
88 if (current->is_alive_and_older_than(last_sweep)) {
89 write_event(current, edge_store);
90 ++count;
91 }
92 current = prev;
93 }
94
95 if (count > 0) {
96 // serialize associated checkpoints and potential chains
97 ObjectSampleCheckpoint::write(object_sampler, edge_store, emit_all, _thread);
98 }
99 return count;
100 }
101
102 static int array_size(const oop object) {
103 assert(object != NULL, "invariant");
104 if (object->is_array()) {
105 return arrayOop(object)->length();
106 }
107 return min_jint;
108 }
109
110 void EventEmitter::write_event(const ObjectSample* sample, EdgeStore* edge_store) {
111 assert(sample != NULL, "invariant");
112 assert(!sample->is_dead(), "invariant");
113 assert(edge_store != NULL, "invariant");
114 assert(_jfr_thread_local != NULL, "invariant");
115
116 traceid gc_root_id = 0;
117 const Edge* edge = NULL;
118 if (SafepointSynchronize::is_at_safepoint()) {
119 if (!sample->object()->mark().is_marked()) {
120 edge = (const Edge*)(sample->object())->mark().to_pointer();
121 }
122 }
123 if (edge == NULL) {
124 // In order to dump out a representation of the event
125 // even though it was not reachable / too long to reach,
126 // we need to register a top level edge for this object.
127 edge = edge_store->put(UnifiedOopRef::encode_in_native(sample->object_addr()));
128 } else {
129 gc_root_id = edge_store->gc_root_id(edge);
130 }
131
132 assert(edge != NULL, "invariant");
133 const traceid object_id = edge_store->get_id(edge);
134 assert(object_id != 0, "invariant");
135
136 Tickspan object_age = Ticks(_start_time.value()) - sample->allocation_time();
137
138 EventOldObjectSample e(UNTIMED);
139 e.set_starttime(_start_time);
140 e.set_endtime(_end_time);
141 e.set_allocationTime(sample->allocation_time());
142 e.set_objectAge(object_age);
143 e.set_lastKnownHeapUsage(sample->heap_used_at_last_gc());
144 e.set_object(object_id);
145 e.set_arrayElements(array_size(edge->pointee()));
146 e.set_root(gc_root_id);
147
148 // Temporarily assigning both the stack trace id and thread id
149 // onto the thread local data structure of the emitter thread (for the duration
150 // of the commit() call). This trick provides a means to override
151 // the event generation mechanism by injecting externally provided id's.
152 // At this particular location, it allows us to emit an old object event
153 // supplying information from where the actual sampling occurred.
154 _jfr_thread_local->set_cached_stack_trace_id(sample->stack_trace_id());
155 assert(sample->has_thread(), "invariant");
156 _jfr_thread_local->set_thread_id(sample->thread_id());
157 e.commit();
158 }