1 
   2 /*
   3  * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "gc/parallel/gcTaskManager.hpp"
  28 #include "gc/parallel/gcTaskThread.hpp"
  29 #include "gc/shared/gcId.hpp"
  30 #include "memory/allocation.hpp"
  31 #include "memory/allocation.inline.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "runtime/handles.hpp"
  34 #include "runtime/handles.inline.hpp"
  35 #include "runtime/os.hpp"
  36 #include "runtime/thread.hpp"
  37 
  38 GCTaskThread::GCTaskThread(GCTaskManager* manager,
  39                            uint           which,
  40                            uint           processor_id) :
  41   _manager(manager),
  42   _processor_id(processor_id),
  43   _time_stamps(NULL),
  44   _time_stamp_index(0)
  45 {
  46   if (!os::create_thread(this, os::pgc_thread))
  47     vm_exit_out_of_memory(0, OOM_MALLOC_ERROR, "Cannot create GC thread. Out of system resources.");
  48 
  49   if (PrintGCTaskTimeStamps) {
  50     _time_stamps = NEW_C_HEAP_ARRAY(GCTaskTimeStamp, GCTaskTimeStampEntries, mtGC);
  51 
  52     guarantee(_time_stamps != NULL, "Sanity");
  53   }
  54   set_id(which);
  55   set_name("ParGC Thread#%d", which);
  56 }
  57 
  58 GCTaskThread::~GCTaskThread() {
  59   if (_time_stamps != NULL) {
  60     FREE_C_HEAP_ARRAY(GCTaskTimeStamp, _time_stamps);
  61   }
  62 }
  63 
  64 void GCTaskThread::start() {
  65   os::start_thread(this);
  66 }
  67 
  68 GCTaskTimeStamp* GCTaskThread::time_stamp_at(uint index) {
  69   guarantee(index < GCTaskTimeStampEntries, "increase GCTaskTimeStampEntries");
  70 
  71   return &(_time_stamps[index]);
  72 }
  73 
  74 void GCTaskThread::print_task_time_stamps() {
  75   assert(PrintGCTaskTimeStamps, "Sanity");
  76   assert(_time_stamps != NULL, "Sanity (Probably set PrintGCTaskTimeStamps late)");
  77 
  78   tty->print_cr("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     tty->print_cr("\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 // GC workers get tasks from the GCTaskManager and execute
  92 // them in this method.  If there are no tasks to execute,
  93 // the GC workers wait in the GCTaskManager's get_task()
  94 // for tasks to be enqueued for execution.
  95 
  96 void GCTaskThread::run() {
  97   // Set up the thread for stack overflow support
  98   this->record_stack_base_and_size();
  99   this->initialize_thread_local_storage();
 100   this->initialize_named_thread();
 101   // Bind yourself to your processor.
 102   if (processor_id() != GCTaskManager::sentinel_worker()) {
 103     if (TraceGCTaskThread) {
 104       tty->print_cr("GCTaskThread::run: "
 105                     "  binding to processor %u", processor_id());
 106     }
 107     if (!os::bind_to_processor(processor_id())) {
 108       DEBUG_ONLY(
 109         warning("Couldn't bind GCTaskThread %u to processor %u",
 110                       which(), processor_id());
 111       )
 112     }
 113   }
 114   // Part of thread setup.
 115   // ??? Are these set up once here to make subsequent ones fast?
 116   HandleMark   hm_outer;
 117   ResourceMark rm_outer;
 118 
 119   TimeStamp timer;
 120 
 121   for (;/* ever */;) {
 122     // These are so we can flush the resources allocated in the inner loop.
 123     HandleMark   hm_inner;
 124     ResourceMark rm_inner;
 125     for (; /* break */; ) {
 126       // This will block until there is a task to be gotten.
 127       GCTask* task = manager()->get_task(which());
 128       GCIdMark gc_id_mark(task->gc_id());
 129       // Record if this is an idle task for later use.
 130       bool is_idle_task = task->is_idle_task();
 131       // In case the update is costly
 132       if (PrintGCTaskTimeStamps) {
 133         timer.update();
 134       }
 135 
 136       jlong entry_time = timer.ticks();
 137       char* name = task->name();
 138 
 139       // If this is the barrier task, it can be destroyed
 140       // by the GC task manager once the do_it() executes.
 141       task->do_it(manager(), which());
 142 
 143       // Use the saved value of is_idle_task because references
 144       // using "task" are not reliable for the barrier task.
 145       if (!is_idle_task) {
 146         manager()->note_completion(which());
 147 
 148         if (PrintGCTaskTimeStamps) {
 149           assert(_time_stamps != NULL,
 150             "Sanity (PrintGCTaskTimeStamps set late?)");
 151 
 152           timer.update();
 153 
 154           GCTaskTimeStamp* time_stamp = time_stamp_at(_time_stamp_index++);
 155 
 156           time_stamp->set_name(name);
 157           time_stamp->set_entry_time(entry_time);
 158           time_stamp->set_exit_time(timer.ticks());
 159         }
 160       } else {
 161         // idle tasks complete outside the normal accounting
 162         // so that a task can complete without waiting for idle tasks.
 163         // They have to be terminated separately.
 164         IdleGCTask::destroy((IdleGCTask*)task);
 165         set_is_working(true);
 166       }
 167 
 168       // Check if we should release our inner resources.
 169       if (manager()->should_release_resources(which())) {
 170         manager()->note_release(which());
 171         break;
 172       }
 173     }
 174   }
 175 }