1 /*
  2  * Copyright (c) 2002, 2018, 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 
 39 GCTaskThread::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 
 51 GCTaskThread::~GCTaskThread() {
 52   if (_time_stamps != NULL) {
 53     FREE_C_HEAP_ARRAY(GCTaskTimeStamp, _time_stamps);
 54   }
 55 }
 56 
 57 void 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 
 75 GCTaskTimeStamp* 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     if (!Atomic::replace_if_null(time_stamps, &_time_stamps)) {
 81       // Someone already setup the time stamps
 82       FREE_C_HEAP_ARRAY(GCTaskTimeStamp, time_stamps);
 83     }
 84   }
 85   return &(_time_stamps[index]);
 86 }
 87 
 88 void GCTaskThread::print_task_time_stamps() {
 89   assert(log_is_enabled(Debug, gc, task, time), "Sanity");
 90 
 91   // Since _time_stamps is now lazily allocated we need to check that it
 92   // has in fact been allocated when calling this function.
 93   if (_time_stamps != NULL) {
 94     log_debug(gc, task, time)("GC-Thread %u entries: %d%s", id(),
 95                               _time_stamp_index,
 96                               _time_stamp_index >= GCTaskTimeStampEntries ? " (overflow)" : "");
 97     const uint max_index = MIN2(_time_stamp_index, GCTaskTimeStampEntries);
 98     for (uint i = 0; i < max_index; i++) {
 99       GCTaskTimeStamp* time_stamp = time_stamp_at(i);
100       log_debug(gc, task, time)("\t[ %s " JLONG_FORMAT " " JLONG_FORMAT " ]",
101                                 time_stamp->name(),
102                                 time_stamp->entry_time(),
103                                 time_stamp->exit_time());
104     }
105 
106     // Reset after dumping the data
107     _time_stamp_index = 0;
108   }
109 }
110 
111 // GC workers get tasks from the GCTaskManager and execute
112 // them in this method.  If there are no tasks to execute,
113 // the GC workers wait in the GCTaskManager's get_task()
114 // for tasks to be enqueued for execution.
115 
116 void GCTaskThread::run() {
117   // Bind yourself to your processor.
118   if (processor_id() != GCTaskManager::sentinel_worker()) {
119     log_trace(gc, task, thread)("GCTaskThread::run: binding to processor %u", processor_id());
120     if (!os::bind_to_processor(processor_id())) {
121       DEBUG_ONLY(
122         log_warning(gc)("Couldn't bind GCTaskThread %u to processor %u",
123                         which(), processor_id());
124       )
125     }
126   }
127   // Part of thread setup.
128   // ??? Are these set up once here to make subsequent ones fast?
129   HandleMark   hm_outer;
130   ResourceMark rm_outer;
131 
132   TimeStamp timer;
133 
134   for (;/* ever */;) {
135     // These are so we can flush the resources allocated in the inner loop.
136     HandleMark   hm_inner;
137     ResourceMark rm_inner;
138     for (; /* break */; ) {
139       // This will block until there is a task to be gotten.
140       GCTask* task = manager()->get_task(which());
141       GCIdMark gc_id_mark(task->gc_id());
142       // Record if this is an idle task for later use.
143       bool is_idle_task = task->is_idle_task();
144       // In case the update is costly
145       if (log_is_enabled(Debug, gc, task, time)) {
146         timer.update();
147       }
148 
149       jlong entry_time = timer.ticks();
150       char* name = task->name();
151 
152       // If this is the barrier task, it can be destroyed
153       // by the GC task manager once the do_it() executes.
154       task->do_it(manager(), which());
155 
156       // Use the saved value of is_idle_task because references
157       // using "task" are not reliable for the barrier task.
158       if (!is_idle_task) {
159         manager()->note_completion(which());
160 
161         if (log_is_enabled(Debug, gc, task, time)) {
162           timer.update();
163           add_task_timestamp(name, entry_time, timer.ticks());
164         }
165       } else {
166         // idle tasks complete outside the normal accounting
167         // so that a task can complete without waiting for idle tasks.
168         // They have to be terminated separately.
169         IdleGCTask::destroy((IdleGCTask*)task);
170         set_is_working(true);
171       }
172 
173       // Check if we should release our inner resources.
174       if (manager()->should_release_resources(which())) {
175         manager()->note_release(which());
176         break;
177       }
178     }
179   }
180 }