1 /*

     2  * Copyright (c) 2002, 2019, 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       }

   171 

   172       // Check if we should release our inner resources.

   173       if (manager()->should_release_resources(which())) {

   174         manager()->note_release(which());

   175         break;

   176       }

   177     }

   178   }

   179 }