1/*
2 * Copyright (c) 2002, 2017, 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/parallel/gcTaskManager.hpp"
27#include "gc/parallel/gcTaskThread.hpp"
28#include "gc/shared/gcId.hpp"
29#include "logging/log.hpp"
30#include "memory/allocation.hpp"
31#include "memory/allocation.inline.hpp"
32#include "memory/resourceArea.hpp"
33#include "runtime/atomic.hpp"
34#include "runtime/handles.hpp"
35#include "runtime/handles.inline.hpp"
36#include "runtime/os.hpp"
37#include "runtime/thread.hpp"
38
39GCTaskThread::GCTaskThread(GCTaskManager* manager,
40                           uint           which,
41                           uint           processor_id) :
42  _manager(manager),
43  _processor_id(processor_id),
44  _time_stamps(NULL),
45  _time_stamp_index(0)
46{
47  set_id(which);
48  set_name("%s#%d", manager->group_name(), which);
49}
50
51GCTaskThread::~GCTaskThread() {
52  if (_time_stamps != NULL) {
53    FREE_C_HEAP_ARRAY(GCTaskTimeStamp, _time_stamps);
54  }
55}
56
57void GCTaskThread::add_task_timestamp(const char* name, jlong t_entry, jlong t_exit) {
58  if (_time_stamp_index < GCTaskTimeStampEntries) {
59    GCTaskTimeStamp* time_stamp = time_stamp_at(_time_stamp_index);
60    time_stamp->set_name(name);
61    time_stamp->set_entry_time(t_entry);
62    time_stamp->set_exit_time(t_exit);
63  } else {
64    if (_time_stamp_index ==  GCTaskTimeStampEntries) {
65      log_warning(gc, task, time)("GC-thread %u: Too many timestamps, ignoring future ones. "
66                                  "Increase GCTaskTimeStampEntries to get more info.",
67                                  id());
68    }
69    // Let _time_stamp_index keep counting to give the user an idea about how many
70    // are needed.
71  }
72  _time_stamp_index++;
73}
74
75GCTaskTimeStamp* GCTaskThread::time_stamp_at(uint index) {
76  assert(index < GCTaskTimeStampEntries, "Precondition");
77  if (_time_stamps == NULL) {
78    // We allocate the _time_stamps array lazily since logging can be enabled dynamically
79    GCTaskTimeStamp* time_stamps = NEW_C_HEAP_ARRAY(GCTaskTimeStamp, GCTaskTimeStampEntries, mtGC);
80    void* old = Atomic::cmpxchg_ptr(time_stamps, &_time_stamps, NULL);
81    if (old != NULL) {
82      // Someone already setup the time stamps
83      FREE_C_HEAP_ARRAY(GCTaskTimeStamp, time_stamps);
84    }
85  }
86  return &(_time_stamps[index]);
87}
88
89void GCTaskThread::print_task_time_stamps() {
90  assert(log_is_enabled(Debug, gc, task, time), "Sanity");
91
92  // Since _time_stamps is now lazily allocated we need to check that it
93  // has in fact been allocated when calling this function.
94  if (_time_stamps != NULL) {
95    log_debug(gc, task, time)("GC-Thread %u entries: %d%s", id(),
96                              _time_stamp_index,
97                              _time_stamp_index >= GCTaskTimeStampEntries ? " (overflow)" : "");
98    const uint max_index = MIN2(_time_stamp_index, GCTaskTimeStampEntries);
99    for (uint i = 0; i < max_index; i++) {
100      GCTaskTimeStamp* time_stamp = time_stamp_at(i);
101      log_debug(gc, task, time)("\t[ %s " JLONG_FORMAT " " JLONG_FORMAT " ]",
102                                time_stamp->name(),
103                                time_stamp->entry_time(),
104                                time_stamp->exit_time());
105    }
106
107    // Reset after dumping the data
108    _time_stamp_index = 0;
109  }
110}
111
112// GC workers get tasks from the GCTaskManager and execute
113// them in this method.  If there are no tasks to execute,
114// the GC workers wait in the GCTaskManager's get_task()
115// for tasks to be enqueued for execution.
116
117void GCTaskThread::run() {
118  // Set up the thread for stack overflow support
119  this->record_stack_base_and_size();
120  this->initialize_named_thread();
121  // Bind yourself to your processor.
122  if (processor_id() != GCTaskManager::sentinel_worker()) {
123    log_trace(gc, task, thread)("GCTaskThread::run: binding to processor %u", processor_id());
124    if (!os::bind_to_processor(processor_id())) {
125      DEBUG_ONLY(
126        log_warning(gc)("Couldn't bind GCTaskThread %u to processor %u",
127                        which(), processor_id());
128      )
129    }
130  }
131  // Part of thread setup.
132  // ??? Are these set up once here to make subsequent ones fast?
133  HandleMark   hm_outer;
134  ResourceMark rm_outer;
135
136  TimeStamp timer;
137
138  for (;/* ever */;) {
139    // These are so we can flush the resources allocated in the inner loop.
140    HandleMark   hm_inner;
141    ResourceMark rm_inner;
142    for (; /* break */; ) {
143      // This will block until there is a task to be gotten.
144      GCTask* task = manager()->get_task(which());
145      GCIdMark gc_id_mark(task->gc_id());
146      // Record if this is an idle task for later use.
147      bool is_idle_task = task->is_idle_task();
148      // In case the update is costly
149      if (log_is_enabled(Debug, gc, task, time)) {
150        timer.update();
151      }
152
153      jlong entry_time = timer.ticks();
154      char* name = task->name();
155
156      // If this is the barrier task, it can be destroyed
157      // by the GC task manager once the do_it() executes.
158      task->do_it(manager(), which());
159
160      // Use the saved value of is_idle_task because references
161      // using "task" are not reliable for the barrier task.
162      if (!is_idle_task) {
163        manager()->note_completion(which());
164
165        if (log_is_enabled(Debug, gc, task, time)) {
166          timer.update();
167          add_task_timestamp(name, entry_time, timer.ticks());
168        }
169      } else {
170        // idle tasks complete outside the normal accounting
171        // so that a task can complete without waiting for idle tasks.
172        // They have to be terminated separately.
173        IdleGCTask::destroy((IdleGCTask*)task);
174        set_is_working(true);
175      }
176
177      // Check if we should release our inner resources.
178      if (manager()->should_release_resources(which())) {
179        manager()->note_release(which());
180        break;
181      }
182    }
183  }
184}
185