1 /*
   2  * Copyright (c) 2002, 2016, 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 GCTaskTimeStamp* GCTaskThread::time_stamp_at(uint index) {
  58   guarantee(index < GCTaskTimeStampEntries, "increase GCTaskTimeStampEntries");
  59   if (_time_stamps == NULL) {
  60     // We allocate the _time_stamps array lazily since logging can be enabled dynamically
  61     GCTaskTimeStamp* time_stamps = NEW_C_HEAP_ARRAY(GCTaskTimeStamp, GCTaskTimeStampEntries, mtGC);
  62     void* old = Atomic::cmpxchg_ptr(time_stamps, &_time_stamps, NULL);
  63     if (old != NULL) {
  64       // Someone already setup the time stamps
  65       FREE_C_HEAP_ARRAY(GCTaskTimeStamp, time_stamps);
  66     }
  67   }
  68 
  69   return &(_time_stamps[index]);
  70 }
  71 
  72 void GCTaskThread::print_task_time_stamps() {
  73   assert(log_is_enabled(Debug, gc, task, time), "Sanity");
  74 
  75   // Since _time_stamps is now lazily allocated we need to check that it
  76   // has in fact been allocated when calling this function.
  77   if (_time_stamps != NULL) {
  78     log_debug(gc, task, time)("GC-Thread %u entries: %d", id(), _time_stamp_index);
  79     for(uint i=0; i<_time_stamp_index; i++) {
  80       GCTaskTimeStamp* time_stamp = time_stamp_at(i);
  81       log_debug(gc, task, time)("\t[ %s " JLONG_FORMAT " " JLONG_FORMAT " ]",
  82                                 time_stamp->name(),
  83                                 time_stamp->entry_time(),
  84                                 time_stamp->exit_time());
  85     }
  86 
  87     // Reset after dumping the data
  88     _time_stamp_index = 0;
  89   }
  90 }
  91 
  92 // GC workers get tasks from the GCTaskManager and execute
  93 // them in this method.  If there are no tasks to execute,
  94 // the GC workers wait in the GCTaskManager's get_task()
  95 // for tasks to be enqueued for execution.
  96 
  97 void GCTaskThread::run() {
  98   // Set up the thread for stack overflow support
  99   this->record_stack_base_and_size();
 100   this->initialize_named_thread();
 101   // Bind yourself to your processor.
 102   if (processor_id() != GCTaskManager::sentinel_worker()) {
 103     log_trace(gc, task, thread)("GCTaskThread::run: binding to processor %u", processor_id());
 104     if (!os::bind_to_processor(processor_id())) {
 105       DEBUG_ONLY(
 106         log_warning(gc)("Couldn't bind GCTaskThread %u to processor %u",
 107                         which(), processor_id());
 108       )
 109     }
 110   }
 111   // Part of thread setup.
 112   // ??? Are these set up once here to make subsequent ones fast?
 113   HandleMark   hm_outer;
 114   ResourceMark rm_outer;
 115 
 116   TimeStamp timer;
 117 
 118   for (;/* ever */;) {
 119     // These are so we can flush the resources allocated in the inner loop.
 120     HandleMark   hm_inner;
 121     ResourceMark rm_inner;
 122     for (; /* break */; ) {
 123       // This will block until there is a task to be gotten.
 124       GCTask* task = manager()->get_task(which());
 125       GCIdMark gc_id_mark(task->gc_id());
 126       // Record if this is an idle task for later use.
 127       bool is_idle_task = task->is_idle_task();
 128       // In case the update is costly
 129       if (log_is_enabled(Debug, gc, task, time)) {
 130         timer.update();
 131       }
 132 
 133       jlong entry_time = timer.ticks();
 134       char* name = task->name();
 135 
 136       // If this is the barrier task, it can be destroyed
 137       // by the GC task manager once the do_it() executes.
 138       task->do_it(manager(), which());
 139 
 140       // Use the saved value of is_idle_task because references
 141       // using "task" are not reliable for the barrier task.
 142       if (!is_idle_task) {
 143         manager()->note_completion(which());
 144 
 145         if (log_is_enabled(Debug, gc, task, time)) {
 146           timer.update();
 147 
 148           GCTaskTimeStamp* time_stamp = time_stamp_at(_time_stamp_index);
 149 
 150           time_stamp->set_name(name);
 151           time_stamp->set_entry_time(entry_time);
 152           time_stamp->set_exit_time(timer.ticks());
 153 
 154           // Update the index after we have set up the entry correctly since
 155           // GCTaskThread::print_task_time_stamps() may read this value concurrently.
 156           _time_stamp_index++;
 157         }
 158       } else {
 159         // idle tasks complete outside the normal accounting
 160         // so that a task can complete without waiting for idle tasks.
 161         // They have to be terminated separately.
 162         IdleGCTask::destroy((IdleGCTask*)task);
 163         set_is_working(true);
 164       }
 165 
 166       // Check if we should release our inner resources.
 167       if (manager()->should_release_resources(which())) {
 168         manager()->note_release(which());
 169         break;
 170       }
 171     }
 172   }
 173 }