rev 4773 : 8005849: JEP 167: Event-Based JVM Tracing
Reviewed-by: acorn, coleenp, sla
Contributed-by: Karen Kinnear <karen.kinnear@oracle.com>, Bengt Rutisson <bengt.rutisson@oracle.com>, Calvin Cheung <calvin.cheung@oracle.com>, Erik Gahlin <erik.gahlin@oracle.com>, Erik Helin <erik.helin@oracle.com>, Jesper Wilhelmsson <jesper.wilhelmsson@oracle.com>, Keith McGuigan <keith.mcguigan@oracle.com>, Mattias Tobiasson <mattias.tobiasson@oracle.com>, Markus Gronlund <markus.gronlund@oracle.com>, Mikael Auno <mikael.auno@oracle.com>, Nils Eliasson <nils.eliasson@oracle.com>, Nils Loodin <nils.loodin@oracle.com>, Rickard Backman <rickard.backman@oracle.com>, Staffan Larsen <staffan.larsen@oracle.com>, Stefan Karlsson <stefan.karlsson@oracle.com>, Yekaterina Kantserova <yekaterina.kantserova@oracle.com>

   1 /*
   2  * Copyright (c) 2005, 2013, 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_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"
  27 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  28 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
  29 #include "gc_implementation/shared/gcTimer.hpp"
  30 #include "gc_implementation/shared/gcTraceTime.hpp"
  31 #include "gc_implementation/shared/isGCActiveMark.hpp"
  32 #include "memory/gcLocker.inline.hpp"
  33 #include "runtime/interfaceSupport.hpp"
  34 #include "runtime/os.hpp"
  35 #include "utilities/dtrace.hpp"
  36 
  37 
  38 #ifndef USDT2
  39 HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__begin);
  40 HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__end);
  41 
  42 HS_DTRACE_PROBE_DECL(hs_private, cms__remark__begin);
  43 HS_DTRACE_PROBE_DECL(hs_private, cms__remark__end);
  44 #endif /* !USDT2 */
  45 
  46 //////////////////////////////////////////////////////////
  47 // Methods in abstract class VM_CMS_Operation
  48 //////////////////////////////////////////////////////////
  49 void VM_CMS_Operation::acquire_pending_list_lock() {
  50   // The caller may block while communicating
  51   // with the SLT thread in order to acquire/release the PLL.
  52   ConcurrentMarkSweepThread::slt()->
  53     manipulatePLL(SurrogateLockerThread::acquirePLL);
  54 }
  55 
  56 void VM_CMS_Operation::release_and_notify_pending_list_lock() {
  57   // The caller may block while communicating
  58   // with the SLT thread in order to acquire/release the PLL.
  59   ConcurrentMarkSweepThread::slt()->
  60     manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
  61 }
  62 
  63 void VM_CMS_Operation::verify_before_gc() {
  64   if (VerifyBeforeGC &&
  65       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
  66     GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm);
  67     HandleMark hm;
  68     FreelistLocker x(_collector);
  69     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
  70     Universe::heap()->prepare_for_verify();
  71     Universe::verify();
  72   }
  73 }
  74 
  75 void VM_CMS_Operation::verify_after_gc() {
  76   if (VerifyAfterGC &&
  77       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
  78     GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm);
  79     HandleMark hm;
  80     FreelistLocker x(_collector);
  81     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
  82     Universe::verify();
  83   }
  84 }
  85 
  86 bool VM_CMS_Operation::lost_race() const {
  87   if (CMSCollector::abstract_state() == CMSCollector::Idling) {
  88     // We lost a race to a foreground collection
  89     // -- there's nothing to do
  90     return true;
  91   }
  92   assert(CMSCollector::abstract_state() == legal_state(),
  93          "Inconsistent collector state?");
  94   return false;
  95 }
  96 
  97 bool VM_CMS_Operation::doit_prologue() {
  98   assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
  99   assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
 100   assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
 101          "Possible deadlock");
 102 
 103   if (needs_pll()) {
 104     acquire_pending_list_lock();
 105   }
 106   // Get the Heap_lock after the pending_list_lock.
 107   Heap_lock->lock();
 108   if (lost_race()) {
 109     assert(_prologue_succeeded == false, "Initialized in c'tor");
 110     Heap_lock->unlock();
 111     if (needs_pll()) {
 112       release_and_notify_pending_list_lock();
 113     }
 114   } else {
 115     _prologue_succeeded = true;
 116   }
 117   return _prologue_succeeded;
 118 }
 119 
 120 void VM_CMS_Operation::doit_epilogue() {
 121   assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
 122   assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
 123   assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
 124          "Possible deadlock");
 125 
 126   // Release the Heap_lock first.
 127   Heap_lock->unlock();
 128   if (needs_pll()) {
 129     release_and_notify_pending_list_lock();
 130   }
 131 }
 132 
 133 //////////////////////////////////////////////////////////
 134 // Methods in class VM_CMS_Initial_Mark
 135 //////////////////////////////////////////////////////////
 136 void VM_CMS_Initial_Mark::doit() {
 137   if (lost_race()) {
 138     // Nothing to do.
 139     return;
 140   }
 141 #ifndef USDT2
 142   HS_DTRACE_PROBE(hs_private, cms__initmark__begin);
 143 #else /* USDT2 */
 144   HS_PRIVATE_CMS_INITMARK_BEGIN(
 145                                 );
 146 #endif /* USDT2 */
 147 
 148   _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark", os::elapsed_counter());
 149 
 150   GenCollectedHeap* gch = GenCollectedHeap::heap();
 151   GCCauseSetter gccs(gch, GCCause::_cms_initial_mark);
 152 
 153   VM_CMS_Operation::verify_before_gc();
 154 
 155   IsGCActiveMark x; // stop-world GC active
 156   _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, gch->gc_cause());
 157 
 158   VM_CMS_Operation::verify_after_gc();
 159 
 160   _collector->_gc_timer_cm->register_gc_pause_end(os::elapsed_counter());
 161 
 162 #ifndef USDT2
 163   HS_DTRACE_PROBE(hs_private, cms__initmark__end);
 164 #else /* USDT2 */
 165   HS_PRIVATE_CMS_INITMARK_END(
 166                                 );
 167 #endif /* USDT2 */
 168 }
 169 
 170 //////////////////////////////////////////////////////////
 171 // Methods in class VM_CMS_Final_Remark_Operation
 172 //////////////////////////////////////////////////////////
 173 void VM_CMS_Final_Remark::doit() {
 174   if (lost_race()) {
 175     // Nothing to do.
 176     return;
 177   }
 178 #ifndef USDT2
 179   HS_DTRACE_PROBE(hs_private, cms__remark__begin);
 180 #else /* USDT2 */
 181   HS_PRIVATE_CMS_REMARK_BEGIN(
 182                                 );
 183 #endif /* USDT2 */
 184 
 185   _collector->_gc_timer_cm->register_gc_pause_start("Final Mark", os::elapsed_counter());
 186 
 187   GenCollectedHeap* gch = GenCollectedHeap::heap();
 188   GCCauseSetter gccs(gch, GCCause::_cms_final_remark);
 189 
 190   VM_CMS_Operation::verify_before_gc();
 191 
 192   IsGCActiveMark x; // stop-world GC active
 193   _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause());
 194 
 195   VM_CMS_Operation::verify_after_gc();
 196 
 197   _collector->save_heap_summary();
 198   _collector->_gc_timer_cm->register_gc_pause_end(os::elapsed_counter());
 199 
 200 #ifndef USDT2
 201   HS_DTRACE_PROBE(hs_private, cms__remark__end);
 202 #else /* USDT2 */
 203   HS_PRIVATE_CMS_REMARK_END(
 204                                 );
 205 #endif /* USDT2 */
 206 }
 207 
 208 // VM operation to invoke a concurrent collection of a
 209 // GenCollectedHeap heap.
 210 void VM_GenCollectFullConcurrent::doit() {
 211   assert(Thread::current()->is_VM_thread(), "Should be VM thread");
 212   assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected");
 213 
 214   GenCollectedHeap* gch = GenCollectedHeap::heap();
 215   if (_gc_count_before == gch->total_collections()) {
 216     // The "full" of do_full_collection call below "forces"
 217     // a collection; the second arg, 0, below ensures that
 218     // only the young gen is collected. XXX In the future,
 219     // we'll probably need to have something in this interface
 220     // to say do this only if we are sure we will not bail
 221     // out to a full collection in this attempt, but that's
 222     // for the future.
 223     assert(SafepointSynchronize::is_at_safepoint(),
 224       "We can only be executing this arm of if at a safepoint");
 225     GCCauseSetter gccs(gch, _gc_cause);
 226     gch->do_full_collection(gch->must_clear_all_soft_refs(),
 227                             0 /* collect only youngest gen */);
 228   } // Else no need for a foreground young gc
 229   assert((_gc_count_before < gch->total_collections()) ||
 230          (GC_locker::is_active() /* gc may have been skipped */
 231           && (_gc_count_before == gch->total_collections())),
 232          "total_collections() should be monotonically increasing");
 233 
 234   MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 235   assert(_full_gc_count_before <= gch->total_full_collections(), "Error");
 236   if (gch->total_full_collections() == _full_gc_count_before) {
 237     // Disable iCMS until the full collection is done, and
 238     // remember that we did so.
 239     CMSCollector::disable_icms();
 240     _disabled_icms = true;
 241     // In case CMS thread was in icms_wait(), wake it up.
 242     CMSCollector::start_icms();
 243     // Nudge the CMS thread to start a concurrent collection.
 244     CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause);
 245   } else {
 246     assert(_full_gc_count_before < gch->total_full_collections(), "Error");
 247     FullGCCount_lock->notify_all();  // Inform the Java thread its work is done
 248   }
 249 }
 250 
 251 bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const {
 252   Thread* thr = Thread::current();
 253   assert(thr != NULL, "Unexpected tid");
 254   if (!thr->is_Java_thread()) {
 255     assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread");
 256     GenCollectedHeap* gch = GenCollectedHeap::heap();
 257     if (_gc_count_before != gch->total_collections()) {
 258       // No need to do a young gc, we'll just nudge the CMS thread
 259       // in the doit() method above, to be executed soon.
 260       assert(_gc_count_before < gch->total_collections(),
 261              "total_collections() should be monotnically increasing");
 262       return false;  // no need for foreground young gc
 263     }
 264   }
 265   return true;       // may still need foreground young gc
 266 }
 267 
 268 
 269 void VM_GenCollectFullConcurrent::doit_epilogue() {
 270   Thread* thr = Thread::current();
 271   assert(thr->is_Java_thread(), "just checking");
 272   JavaThread* jt = (JavaThread*)thr;
 273   // Release the Heap_lock first.
 274   Heap_lock->unlock();
 275   release_and_notify_pending_list_lock();
 276 
 277   // It is fine to test whether completed collections has
 278   // exceeded our request count without locking because
 279   // the completion count is monotonically increasing;
 280   // this will break for very long-running apps when the
 281   // count overflows and wraps around. XXX fix me !!!
 282   // e.g. at the rate of 1 full gc per ms, this could
 283   // overflow in about 1000 years.
 284   GenCollectedHeap* gch = GenCollectedHeap::heap();
 285   if (_gc_cause != GCCause::_gc_locker &&
 286       gch->total_full_collections_completed() <= _full_gc_count_before) {
 287     // maybe we should change the condition to test _gc_cause ==
 288     // GCCause::_java_lang_system_gc, instead of
 289     // _gc_cause != GCCause::_gc_locker
 290     assert(_gc_cause == GCCause::_java_lang_system_gc,
 291            "the only way to get here if this was a System.gc()-induced GC");
 292     assert(ExplicitGCInvokesConcurrent, "Error");
 293     // Now, wait for witnessing concurrent gc cycle to complete,
 294     // but do so in native mode, because we want to lock the
 295     // FullGCEvent_lock, which may be needed by the VM thread
 296     // or by the CMS thread, so we do not want to be suspended
 297     // while holding that lock.
 298     ThreadToNativeFromVM native(jt);
 299     MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 300     // Either a concurrent or a stop-world full gc is sufficient
 301     // witness to our request.
 302     while (gch->total_full_collections_completed() <= _full_gc_count_before) {
 303       FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
 304     }
 305   }
 306   // Enable iCMS back if we disabled it earlier.
 307   if (_disabled_icms) {
 308     CMSCollector::enable_icms();
 309   }
 310 }
--- EOF ---