# HG changeset patch
# User brutisso
# Date 1403177474 -7200
# Node ID 0982ec23da03d077f02dd8e9ff292e456101b8cb
# Parent  5d855d021755ef19aed9c483df6c678199bbcd1d
8043607: Add a GC id as a log decoration similar to PrintGCTimeStamps
Reviewed-by: jwilhelm, ehelin, tschatzl

diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -1999,7 +1999,7 @@
   SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
   gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
 
-  GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL);
+  GCTraceTime t("CMS:MSC ", PrintGCDetails && Verbose, true, NULL, gc_tracer->gc_id());
   if (PrintGC && Verbose && !(GCCause::is_user_requested_gc(gch->gc_cause()))) {
     gclog_or_tty->print_cr("Compact ConcurrentMarkSweepGeneration after %d "
       "collections passed to foreground collector", _full_gcs_since_conc_gc);
@@ -2509,8 +2509,10 @@
   assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),
          "VM thread should have CMS token");
 
+  // The gc id is created in register_foreground_gc_start if this collection is synchronous
+  const GCId gc_id = _collectorState == InitialMarking ? GCId::peek() : _gc_tracer_cm->gc_id();
   NOT_PRODUCT(GCTraceTime t("CMS:MS (foreground) ", PrintGCDetails && Verbose,
-    true, NULL);)
+    true, NULL, gc_id);)
   if (UseAdaptiveSizePolicy) {
     size_policy()->ms_collection_begin();
   }
@@ -3527,6 +3529,7 @@
  public:
   CMSPhaseAccounting(CMSCollector *collector,
                      const char *phase,
+                     const GCId gc_id,
                      bool print_cr = true);
   ~CMSPhaseAccounting();
 
@@ -3535,6 +3538,7 @@
   const char *_phase;
   elapsedTimer _wallclock;
   bool _print_cr;
+  const GCId _gc_id;
 
  public:
   // Not MT-safe; so do not pass around these StackObj's
@@ -3550,15 +3554,15 @@
 
 CMSPhaseAccounting::CMSPhaseAccounting(CMSCollector *collector,
                                        const char *phase,
+                                       const GCId gc_id,
                                        bool print_cr) :
-  _collector(collector), _phase(phase), _print_cr(print_cr) {
+  _collector(collector), _phase(phase), _print_cr(print_cr), _gc_id(gc_id) {
 
   if (PrintCMSStatistics != 0) {
     _collector->resetYields();
   }
   if (PrintGCDetails) {
-    gclog_or_tty->date_stamp(PrintGCDateStamps);
-    gclog_or_tty->stamp(PrintGCTimeStamps);
+    gclog_or_tty->gclog_stamp(_gc_id);
     gclog_or_tty->print_cr("[%s-concurrent-%s-start]",
       _collector->cmsGen()->short_name(), _phase);
   }
@@ -3572,8 +3576,7 @@
   _collector->stopTimer();
   _wallclock.stop();
   if (PrintGCDetails) {
-    gclog_or_tty->date_stamp(PrintGCDateStamps);
-    gclog_or_tty->stamp(PrintGCTimeStamps);
+    gclog_or_tty->gclog_stamp(_gc_id);
     gclog_or_tty->print("[%s-concurrent-%s: %3.3f/%3.3f secs]",
                  _collector->cmsGen()->short_name(),
                  _phase, _collector->timerValue(), _wallclock.seconds());
@@ -3671,7 +3674,7 @@
   setup_cms_unloading_and_verification_state();
 
   NOT_PRODUCT(GCTraceTime t("\ncheckpointRootsInitialWork",
-    PrintGCDetails && Verbose, true, _gc_timer_cm);)
+    PrintGCDetails && Verbose, true, _gc_timer_cm, _gc_tracer_cm->gc_id());)
   if (UseAdaptiveSizePolicy) {
     size_policy()->checkpoint_roots_initial_begin();
   }
@@ -3796,7 +3799,7 @@
 
     CMSTokenSyncWithLocks ts(true, bitMapLock());
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    CMSPhaseAccounting pa(this, "mark", !PrintGCDetails);
+    CMSPhaseAccounting pa(this, "mark", _gc_tracer_cm->gc_id(), !PrintGCDetails);
     res = markFromRootsWork(asynch);
     if (res) {
       _collectorState = Precleaning;
@@ -4519,7 +4522,7 @@
       _start_sampling = false;
     }
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    CMSPhaseAccounting pa(this, "preclean", !PrintGCDetails);
+    CMSPhaseAccounting pa(this, "preclean", _gc_tracer_cm->gc_id(), !PrintGCDetails);
     preclean_work(CMSPrecleanRefLists1, CMSPrecleanSurvivors1);
   }
   CMSTokenSync x(true); // is cms thread
@@ -4548,7 +4551,7 @@
   // we will never do an actual abortable preclean cycle.
   if (get_eden_used() > CMSScheduleRemarkEdenSizeThreshold) {
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    CMSPhaseAccounting pa(this, "abortable-preclean", !PrintGCDetails);
+    CMSPhaseAccounting pa(this, "abortable-preclean", _gc_tracer_cm->gc_id(), !PrintGCDetails);
     // We need more smarts in the abortable preclean
     // loop below to deal with cases where allocation
     // in young gen is very very slow, and our precleaning
@@ -4693,7 +4696,7 @@
     GCTimer *gc_timer = NULL; // Currently not tracing concurrent phases
     rp->preclean_discovered_references(
           rp->is_alive_non_header(), &keep_alive, &complete_trace, &yield_cl,
-          gc_timer);
+          gc_timer, _gc_tracer_cm->gc_id());
   }
 
   if (clean_survivor) {  // preclean the active survivor space(s)
@@ -5036,7 +5039,7 @@
       // expect it to be false and set to true
       FlagSetting fl(gch->_is_gc_active, false);
       NOT_PRODUCT(GCTraceTime t("Scavenge-Before-Remark",
-        PrintGCDetails && Verbose, true, _gc_timer_cm);)
+        PrintGCDetails && Verbose, true, _gc_timer_cm, _gc_tracer_cm->gc_id());)
       int level = _cmsGen->level() - 1;
       if (level >= 0) {
         gch->do_collection(true,        // full (i.e. force, see below)
@@ -5065,7 +5068,7 @@
 void CMSCollector::checkpointRootsFinalWork(bool asynch,
   bool clear_all_soft_refs, bool init_mark_was_synchronous) {
 
-  NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm);)
+  NOT_PRODUCT(GCTraceTime tr("checkpointRootsFinalWork", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());)
 
   assert(haveFreelistLocks(), "must have free list locks");
   assert_lock_strong(bitMapLock());
@@ -5120,11 +5123,11 @@
       // the most recent young generation GC, minus those cleaned up by the
       // concurrent precleaning.
       if (CMSParallelRemarkEnabled && CollectedHeap::use_parallel_gc_threads()) {
-        GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm);
+        GCTraceTime t("Rescan (parallel) ", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
         do_remark_parallel();
       } else {
         GCTraceTime t("Rescan (non-parallel) ", PrintGCDetails, false,
-                    _gc_timer_cm);
+                    _gc_timer_cm, _gc_tracer_cm->gc_id());
         do_remark_non_parallel();
       }
     }
@@ -5137,7 +5140,7 @@
   verify_overflow_empty();
 
   {
-    NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm);)
+    NOT_PRODUCT(GCTraceTime ts("refProcessingWork", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());)
     refProcessingWork(asynch, clear_all_soft_refs);
   }
   verify_work_stacks_empty();
@@ -5922,7 +5925,7 @@
                               NULL,  // space is set further below
                               &_markBitMap, &_markStack, &mrias_cl);
   {
-    GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("grey object rescan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
     // Iterate over the dirty cards, setting the corresponding bits in the
     // mod union table.
     {
@@ -5959,7 +5962,7 @@
     Universe::verify();
   }
   {
-    GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("root rescan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
 
     verify_work_stacks_empty();
 
@@ -5981,7 +5984,7 @@
   }
 
   {
-    GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("visit unhandled CLDs", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
 
     verify_work_stacks_empty();
 
@@ -6000,7 +6003,7 @@
   }
 
   {
-    GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("dirty klass scan", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
 
     verify_work_stacks_empty();
 
@@ -6202,7 +6205,7 @@
                                 _span, &_markBitMap, &_markStack,
                                 &cmsKeepAliveClosure, false /* !preclean */);
   {
-    GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("weak refs processing", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
 
     ReferenceProcessorStats stats;
     if (rp->processing_is_mt()) {
@@ -6227,13 +6230,15 @@
                                         &cmsKeepAliveClosure,
                                         &cmsDrainMarkingStackClosure,
                                         &task_executor,
-                                        _gc_timer_cm);
+                                        _gc_timer_cm,
+                                        _gc_tracer_cm->gc_id());
     } else {
       stats = rp->process_discovered_references(&_is_alive_closure,
                                         &cmsKeepAliveClosure,
                                         &cmsDrainMarkingStackClosure,
                                         NULL,
-                                        _gc_timer_cm);
+                                        _gc_timer_cm,
+                                        _gc_tracer_cm->gc_id());
     }
     _gc_tracer_cm->report_gc_reference_stats(stats);
 
@@ -6244,7 +6249,7 @@
 
   if (should_unload_classes()) {
     {
-      GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm);
+      GCTraceTime t("class unloading", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
 
       // Unload classes and purge the SystemDictionary.
       bool purged_class = SystemDictionary::do_unloading(&_is_alive_closure);
@@ -6257,7 +6262,7 @@
     }
 
     {
-      GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm);
+      GCTraceTime t("scrub symbol table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
       // Clean up unreferenced symbols in symbol table.
       SymbolTable::unlink();
     }
@@ -6266,7 +6271,7 @@
   // CMS doesn't use the StringTable as hard roots when class unloading is turned off.
   // Need to check if we really scanned the StringTable.
   if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) {
-    GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm);
+    GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
     // Delete entries for dead interned strings.
     StringTable::unlink(&_is_alive_closure);
   }
@@ -6333,7 +6338,7 @@
   _intra_sweep_timer.start();
   if (asynch) {
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    CMSPhaseAccounting pa(this, "sweep", !PrintGCDetails);
+    CMSPhaseAccounting pa(this, "sweep", _gc_tracer_cm->gc_id(), !PrintGCDetails);
     // First sweep the old gen
     {
       CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock(),
@@ -6554,7 +6559,7 @@
     // Clear the mark bitmap (no grey objects to start with)
     // for the next cycle.
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    CMSPhaseAccounting cmspa(this, "reset", !PrintGCDetails);
+    CMSPhaseAccounting cmspa(this, "reset", _gc_tracer_cm->gc_id(), !PrintGCDetails);
 
     HeapWord* curAddr = _markBitMap.startWord();
     while (curAddr < _markBitMap.endWord()) {
@@ -6620,7 +6625,7 @@
 void CMSCollector::do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause) {
   gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
   TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-  GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
+  GCTraceTime t(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer_cm->gc_id());
   TraceCollectorStats tcs(counters());
 
   switch (op) {
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -64,7 +64,7 @@
 void VM_CMS_Operation::verify_before_gc() {
   if (VerifyBeforeGC &&
       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
-    GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm);
+    GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id());
     HandleMark hm;
     FreelistLocker x(_collector);
     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
@@ -76,7 +76,7 @@
 void VM_CMS_Operation::verify_after_gc() {
   if (VerifyAfterGC &&
       GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
-    GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm);
+    GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id());
     HandleMark hm;
     FreelistLocker x(_collector);
     MutexLockerEx  y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/concurrentMark.cpp
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -510,6 +510,7 @@
   _has_overflown(false),
   _concurrent(false),
   _has_aborted(false),
+  _aborted_gc_id(GCId::undefined()),
   _restart_for_overflow(false),
   _concurrent_marking_in_progress(false),
 
@@ -1019,8 +1020,7 @@
       force_overflow()->update();
 
       if (G1Log::fine()) {
-        gclog_or_tty->date_stamp(PrintGCDateStamps);
-        gclog_or_tty->stamp(PrintGCTimeStamps);
+        gclog_or_tty->gclog_stamp(concurrent_gc_id());
         gclog_or_tty->print_cr("[GC concurrent-mark-reset-for-overflow]");
       }
     }
@@ -2464,7 +2464,7 @@
     if (G1Log::finer()) {
       gclog_or_tty->put(' ');
     }
-    GCTraceTime t("GC ref-proc", G1Log::finer(), false, g1h->gc_timer_cm());
+    GCTraceTime t("GC ref-proc", G1Log::finer(), false, g1h->gc_timer_cm(), concurrent_gc_id());
 
     ReferenceProcessor* rp = g1h->ref_processor_cm();
 
@@ -2521,7 +2521,8 @@
                                           &g1_keep_alive,
                                           &g1_drain_mark_stack,
                                           executor,
-                                          g1h->gc_timer_cm());
+                                          g1h->gc_timer_cm(),
+                                          concurrent_gc_id());
     g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
 
     // The do_oop work routines of the keep_alive and drain_marking_stack
@@ -3252,6 +3253,12 @@
   }
   _first_overflow_barrier_sync.abort();
   _second_overflow_barrier_sync.abort();
+  const GCId& gc_id = _g1h->gc_tracer_cm()->gc_id();
+  if (!gc_id.is_undefined()) {
+    // We can do multiple full GCs before ConcurrentMarkThread::run() gets a chance
+    // to detect that it was aborted. Only keep track of the first GC id that we aborted.
+    _aborted_gc_id = gc_id;
+   }
   _has_aborted = true;
 
   SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
@@ -3266,6 +3273,13 @@
   _g1h->register_concurrent_cycle_end();
 }
 
+const GCId& ConcurrentMark::concurrent_gc_id() {
+  if (has_aborted()) {
+    return _aborted_gc_id;
+  }
+  return _g1h->gc_tracer_cm()->gc_id();
+}
+
 static void print_ms_time_info(const char* prefix, const char* name,
                                NumberSeq& ns) {
   gclog_or_tty->print_cr("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/concurrentMark.hpp
--- a/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -26,6 +26,7 @@
 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
 
 #include "gc_implementation/g1/heapRegionSet.hpp"
+#include "gc_implementation/shared/gcId.hpp"
 #include "utilities/taskqueue.hpp"
 
 class G1CollectedHeap;
@@ -444,6 +445,7 @@
   volatile bool           _concurrent;
   // set at the end of a Full GC so that marking aborts
   volatile bool           _has_aborted;
+  GCId                    _aborted_gc_id;
 
   // used when remark aborts due to an overflow to indicate that
   // another concurrent marking phase should start
@@ -825,6 +827,8 @@
 
   bool has_aborted()      { return _has_aborted; }
 
+  const GCId& concurrent_gc_id();
+
   // This prints the global/local fingers. It is used for debugging.
   NOT_PRODUCT(void print_finger();)
 
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -1,4 +1,4 @@
-/*
+ /*
  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -29,6 +29,7 @@
 #include "gc_implementation/g1/g1Log.hpp"
 #include "gc_implementation/g1/g1MMUTracker.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
+#include "gc_implementation/shared/gcTrace.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/vmThread.hpp"
 
@@ -109,8 +110,7 @@
       double scan_start = os::elapsedTime();
       if (!cm()->has_aborted()) {
         if (G1Log::fine()) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
           gclog_or_tty->print_cr("[GC concurrent-root-region-scan-start]");
         }
 
@@ -118,8 +118,7 @@
 
         double scan_end = os::elapsedTime();
         if (G1Log::fine()) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
           gclog_or_tty->print_cr("[GC concurrent-root-region-scan-end, %1.7lf secs]",
                                  scan_end - scan_start);
         }
@@ -127,8 +126,7 @@
 
       double mark_start_sec = os::elapsedTime();
       if (G1Log::fine()) {
-        gclog_or_tty->date_stamp(PrintGCDateStamps);
-        gclog_or_tty->stamp(PrintGCTimeStamps);
+        gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
         gclog_or_tty->print_cr("[GC concurrent-mark-start]");
       }
 
@@ -151,8 +149,7 @@
           }
 
           if (G1Log::fine()) {
-            gclog_or_tty->date_stamp(PrintGCDateStamps);
-            gclog_or_tty->stamp(PrintGCTimeStamps);
+            gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
             gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf secs]",
                                       mark_end_sec - mark_start_sec);
           }
@@ -167,8 +164,7 @@
                                    "in remark (restart #%d).", iter);
           }
           if (G1Log::fine()) {
-            gclog_or_tty->date_stamp(PrintGCDateStamps);
-            gclog_or_tty->stamp(PrintGCTimeStamps);
+            gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
             gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
           }
         }
@@ -212,8 +208,7 @@
 
         double cleanup_start_sec = os::elapsedTime();
         if (G1Log::fine()) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
           gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
         }
 
@@ -233,8 +228,7 @@
 
         double cleanup_end_sec = os::elapsedTime();
         if (G1Log::fine()) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
           gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf secs]",
                                  cleanup_end_sec - cleanup_start_sec);
         }
@@ -274,8 +268,7 @@
 
       if (cm()->has_aborted()) {
         if (G1Log::fine()) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
+          gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
           gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
         }
       }
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -1305,7 +1305,7 @@
     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
 
     {
-      GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
+      GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
       TraceCollectorStats tcs(g1mm()->full_collection_counters());
       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
 
@@ -3893,8 +3893,7 @@
     return;
   }
 
-  gclog_or_tty->date_stamp(PrintGCDateStamps);
-  gclog_or_tty->stamp(PrintGCTimeStamps);
+  gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
 
   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
@@ -5781,7 +5780,8 @@
                                               &keep_alive,
                                               &drain_queue,
                                               NULL,
-                                              _gc_timer_stw);
+                                              _gc_timer_stw,
+                                              _gc_tracer_stw->gc_id());
   } else {
     // Parallel reference processing
     assert(rp->num_q() == no_of_gc_workers, "sanity");
@@ -5792,7 +5792,8 @@
                                               &keep_alive,
                                               &drain_queue,
                                               &par_task_executor,
-                                              _gc_timer_stw);
+                                              _gc_timer_stw,
+                                              _gc_tracer_stw->gc_id());
   }
 
   _gc_tracer_stw->report_gc_reference_stats(stats);
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/g1MarkSweep.cpp
--- a/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -123,7 +123,7 @@
 void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
                                     bool clear_all_softrefs) {
   // Recursively traverse all live objects and mark them
-  GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer());
+  GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
   GenMarkSweep::trace(" 1");
 
   SharedHeap* sh = SharedHeap::heap();
@@ -148,7 +148,8 @@
                                       &GenMarkSweep::keep_alive,
                                       &GenMarkSweep::follow_stack_closure,
                                       NULL,
-                                      gc_timer());
+                                      gc_timer(),
+                                      gc_tracer()->gc_id());
   gc_tracer()->report_gc_reference_stats(stats);
 
 
@@ -262,7 +263,7 @@
 
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
-  GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer());
+  GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
   GenMarkSweep::trace("2");
 
   // find the first region
@@ -299,7 +300,7 @@
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
   // Adjust the pointers to reflect the new locations
-  GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer());
+  GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
   GenMarkSweep::trace("3");
 
   SharedHeap* sh = SharedHeap::heap();
@@ -362,7 +363,7 @@
   // to use a higher index (saved from phase2) when verifying perm_gen.
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
-  GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer());
+  GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id());
   GenMarkSweep::trace("4");
 
   G1SpaceCompactClosure blk;
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/g1/vm_operations_g1.cpp
--- a/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -226,7 +226,7 @@
 void VM_CGC_Operation::doit() {
   gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
   TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
-  GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm());
+  GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id());
   SharedHeap* sh = SharedHeap::heap();
   // This could go away if CollectedHeap gave access to _gc_is_active...
   if (sh != NULL) {
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parNew/parNewGeneration.cpp
--- a/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -957,7 +957,7 @@
     size_policy->minor_collection_begin();
   }
 
-  GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
+  GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id());
   // Capture heap used before collection (for printing).
   size_t gch_prev_used = gch->used();
 
@@ -1015,14 +1015,14 @@
     ParNewRefProcTaskExecutor task_executor(*this, thread_state_set);
     stats = rp->process_discovered_references(&is_alive, &keep_alive,
                                               &evacuate_followers, &task_executor,
-                                              _gc_timer);
+                                              _gc_timer, gc_tracer.gc_id());
   } else {
     thread_state_set.flush();
     gch->set_par_threads(0);  // 0 ==> non-parallel.
     gch->save_marks();
     stats = rp->process_discovered_references(&is_alive, &keep_alive,
                                               &evacuate_followers, NULL,
-                                              _gc_timer);
+                                              _gc_timer, gc_tracer.gc_id());
   }
   gc_tracer.report_gc_reference_stats(stats);
   if (!promotion_failed()) {
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -53,7 +53,7 @@
   ResourceMark rm;
 
   NOT_PRODUCT(GCTraceTime tm("ThreadRootsMarkingTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
 
@@ -82,7 +82,7 @@
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
   NOT_PRODUCT(GCTraceTime tm("MarkFromRootsTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
@@ -153,7 +153,7 @@
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
   NOT_PRODUCT(GCTraceTime tm("RefProcTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
@@ -209,7 +209,7 @@
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
   NOT_PRODUCT(GCTraceTime tm("StealMarkingTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
 
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
@@ -242,7 +242,7 @@
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
   NOT_PRODUCT(GCTraceTime tm("StealRegionCompactionTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
 
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
@@ -309,7 +309,7 @@
 void UpdateDensePrefixTask::do_it(GCTaskManager* manager, uint which) {
 
   NOT_PRODUCT(GCTraceTime tm("UpdateDensePrefixTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
 
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
@@ -324,7 +324,7 @@
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
   NOT_PRODUCT(GCTraceTime tm("DrainStacksCompactionTask",
-    PrintGCDetails && TraceParallelOldGCTasks, true, NULL));
+    PrintGCDetails && TraceParallelOldGCTasks, true, NULL, PSParallelCompact::gc_tracer()->gc_id()));
 
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -169,7 +169,7 @@
 
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
+    GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
     TraceCollectorStats tcs(counters());
     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
 
@@ -513,7 +513,7 @@
 
 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
   // Recursively traverse all live objects and mark them
-  GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace(" 1");
 
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
@@ -548,7 +548,7 @@
     ref_processor()->setup_policy(clear_all_softrefs);
     const ReferenceProcessorStats& stats =
       ref_processor()->process_discovered_references(
-        is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
+        is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
     gc_tracer()->report_gc_reference_stats(stats);
   }
 
@@ -574,7 +574,7 @@
 
 
 void PSMarkSweep::mark_sweep_phase2() {
-  GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("2");
 
   // Now all live objects are marked, compute the new object addresses.
@@ -604,7 +604,7 @@
 
 void PSMarkSweep::mark_sweep_phase3() {
   // Adjust the pointers to reflect the new locations
-  GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("3");
 
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
@@ -647,7 +647,7 @@
 
 void PSMarkSweep::mark_sweep_phase4() {
   EventMark m("4 compact heap");
-  GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("4");
 
   // All pointers are now adjusted, move objects accordingly
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -978,7 +978,7 @@
   // at each young gen gc.  Do the update unconditionally (even though a
   // promotion failure does not swap spaces) because an unknown number of minor
   // collections will have swapped the spaces an unknown number of times.
-  GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
   ParallelScavengeHeap* heap = gc_heap();
   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
@@ -1021,7 +1021,7 @@
 
 void PSParallelCompact::post_compact()
 {
-  GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("post compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
     // Clear the marking bitmap, summary data and split info.
@@ -1847,7 +1847,7 @@
 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
                                       bool maximum_compaction)
 {
-  GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
   // trace("2");
 
 #ifdef  ASSERT
@@ -2056,7 +2056,7 @@
 
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
+    GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
     TraceCollectorStats tcs(counters());
     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
 
@@ -2351,7 +2351,7 @@
                                       bool maximum_heap_compaction,
                                       ParallelOldTracer *gc_tracer) {
   // Recursively traverse all live objects and mark them
-  GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   ParallelScavengeHeap* heap = gc_heap();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
@@ -2366,7 +2366,7 @@
   ClassLoaderDataGraph::clear_claimed_marks();
 
   {
-    GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
+    GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
     ParallelScavengeHeap::ParStrongRootsScope psrs;
 
@@ -2395,24 +2395,24 @@
 
   // Process reference objects found during marking
   {
-    GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
+    GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
     ReferenceProcessorStats stats;
     if (ref_processor()->processing_is_mt()) {
       RefProcTaskExecutor task_executor;
       stats = ref_processor()->process_discovered_references(
         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
-        &task_executor, &_gc_timer);
+        &task_executor, &_gc_timer, _gc_tracer.gc_id());
     } else {
       stats = ref_processor()->process_discovered_references(
         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
-        &_gc_timer);
+        &_gc_timer, _gc_tracer.gc_id());
     }
 
     gc_tracer->report_gc_reference_stats(stats);
   }
 
-  GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
+  GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   // This is the point where the entire marking should have completed.
   assert(cm->marking_stacks_empty(), "Marking should have completed");
@@ -2451,7 +2451,7 @@
 
 void PSParallelCompact::adjust_roots() {
   // Adjust the pointers to reflect the new locations
-  GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   // Need new claim bits when tracing through and adjusting pointers.
   ClassLoaderDataGraph::clear_claimed_marks();
@@ -2487,7 +2487,7 @@
 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
                                                       uint parallel_gc_threads)
 {
-  GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   // Find the threads that are active
   unsigned int which = 0;
@@ -2561,7 +2561,7 @@
 
 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
                                                     uint parallel_gc_threads) {
-  GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   ParallelCompactData& sd = PSParallelCompact::summary_data();
 
@@ -2643,7 +2643,7 @@
                                      GCTaskQueue* q,
                                      ParallelTaskTerminator* terminator_ptr,
                                      uint parallel_gc_threads) {
-  GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   // Once a thread has drained it's stack, it should try to steal regions from
   // other threads.
@@ -2691,7 +2691,7 @@
 
 void PSParallelCompact::compact() {
   // trace("5");
-  GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
+  GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
@@ -2708,7 +2708,7 @@
   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
 
   {
-    GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
+    GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
 
     gc_task_manager()->execute_and_wait(q);
 
@@ -2722,7 +2722,7 @@
 
   {
     // Update the deferred objects, if any.  Any compaction manager can be used.
-    GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
+    GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
       update_deferred_objects(cm, SpaceId(id));
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -1004,6 +1004,10 @@
   static bool   _dwl_initialized;
 #endif  // #ifdef ASSERT
 
+
+ public:
+  static ParallelOldTracer* gc_tracer() { return &_gc_tracer; }
+
  private:
 
   static void initialize_space_info();
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -331,7 +331,7 @@
 
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
+    GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
     TraceCollectorStats tcs(counters());
     TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
 
@@ -397,7 +397,7 @@
     // We'll use the promotion manager again later.
     PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
     {
-      GCTraceTime tm("Scavenge", false, false, &_gc_timer);
+      GCTraceTime tm("Scavenge", false, false, &_gc_timer, _gc_tracer.gc_id());
       ParallelScavengeHeap::ParStrongRootsScope psrs;
 
       GCTaskQueue* q = GCTaskQueue::create();
@@ -439,7 +439,7 @@
 
     // Process reference objects discovered during scavenge
     {
-      GCTraceTime tm("References", false, false, &_gc_timer);
+      GCTraceTime tm("References", false, false, &_gc_timer, _gc_tracer.gc_id());
 
       reference_processor()->setup_policy(false); // not always_clear
       reference_processor()->set_active_mt_degree(active_workers);
@@ -450,10 +450,10 @@
         PSRefProcTaskExecutor task_executor;
         stats = reference_processor()->process_discovered_references(
           &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
-          &_gc_timer);
+          &_gc_timer, _gc_tracer.gc_id());
       } else {
         stats = reference_processor()->process_discovered_references(
-          &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
+          &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer, _gc_tracer.gc_id());
       }
 
       _gc_tracer.report_gc_reference_stats(stats);
@@ -468,7 +468,7 @@
     }
 
     {
-      GCTraceTime tm("StringTable", false, false, &_gc_timer);
+      GCTraceTime tm("StringTable", false, false, &_gc_timer, _gc_tracer.gc_id());
       // Unlink any dead interned Strings and process the remaining live ones.
       PSScavengeRootsClosure root_closure(promotion_manager);
       StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
@@ -638,7 +638,7 @@
     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
 
     {
-      GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer);
+      GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer, _gc_tracer.gc_id());
 
       CodeCache::prune_scavenge_root_nmethods();
     }
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcId.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/shared/gcId.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/shared/gcId.hpp"
+#include "runtime/safepoint.hpp"
+
+uint GCId::_next_id = 0;
+
+const GCId GCId::create() {
+  return GCId(_next_id++);
+}
+const GCId GCId::peek() {
+  return GCId(_next_id);
+}
+const GCId GCId::undefined() {
+  return GCId(UNDEFINED);
+}
+bool GCId::is_undefined() const {
+  return _id == UNDEFINED;
+}
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcId.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/shared/gcId.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_GCID_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_SHARED_GCID_HPP
+
+#include "memory/allocation.hpp"
+
+class GCId VALUE_OBJ_CLASS_SPEC {
+ private:
+  uint _id;
+  GCId(uint id) : _id(id) {}
+  GCId() { } // Unused
+
+  static uint _next_id;
+  static const uint UNDEFINED = (uint)-1;
+
+ public:
+  uint id() const {
+    assert(_id != UNDEFINED, "Using undefined GC ID");
+    return _id;
+  }
+  bool is_undefined() const;
+
+  static const GCId create();
+  static const GCId peek();
+  static const GCId undefined();
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_GCID_HPP
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcTrace.cpp
--- a/src/share/vm/gc_implementation/shared/gcTrace.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/gcTrace.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -25,6 +25,7 @@
 #include "precompiled.hpp"
 #include "gc_implementation/shared/copyFailedInfo.hpp"
 #include "gc_implementation/shared/gcHeapSummary.hpp"
+#include "gc_implementation/shared/gcId.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/objectCountEventSender.hpp"
@@ -38,19 +39,14 @@
 #include "gc_implementation/g1/evacuationInfo.hpp"
 #endif
 
-#define assert_unset_gc_id() assert(_shared_gc_info.id() == SharedGCInfo::UNSET_GCID, "GC already started?")
-#define assert_set_gc_id() assert(_shared_gc_info.id() != SharedGCInfo::UNSET_GCID, "GC not started?")
-
-static GCId GCTracer_next_gc_id = 0;
-static GCId create_new_gc_id() {
-  return GCTracer_next_gc_id++;
-}
+#define assert_unset_gc_id() assert(_shared_gc_info.gc_id().is_undefined(), "GC already started?")
+#define assert_set_gc_id() assert(!_shared_gc_info.gc_id().is_undefined(), "GC not started?")
 
 void GCTracer::report_gc_start_impl(GCCause::Cause cause, const Ticks& timestamp) {
   assert_unset_gc_id();
 
-  GCId gc_id = create_new_gc_id();
-  _shared_gc_info.set_id(gc_id);
+  GCId gc_id = GCId::create();
+  _shared_gc_info.set_gc_id(gc_id);
   _shared_gc_info.set_cause(cause);
   _shared_gc_info.set_start_timestamp(timestamp);
 }
@@ -62,7 +58,7 @@
 }
 
 bool GCTracer::has_reported_gc_start() const {
-  return _shared_gc_info.id() != SharedGCInfo::UNSET_GCID;
+  return !_shared_gc_info.gc_id().is_undefined();
 }
 
 void GCTracer::report_gc_end_impl(const Ticks& timestamp, TimePartitions* time_partitions) {
@@ -81,7 +77,7 @@
 
   report_gc_end_impl(timestamp, time_partitions);
 
-  _shared_gc_info.set_id(SharedGCInfo::UNSET_GCID);
+  _shared_gc_info.set_gc_id(GCId::undefined());
 }
 
 void GCTracer::report_gc_reference_stats(const ReferenceProcessorStats& rps) const {
@@ -132,7 +128,7 @@
     if (!cit.allocation_failed()) {
       HeapInspection hi(false, false, false, NULL);
       hi.populate_table(&cit, is_alive_cl);
-      ObjectCountEventSenderClosure event_sender(_shared_gc_info.id(), cit.size_of_instances_in_words(), Ticks::now());
+      ObjectCountEventSenderClosure event_sender(_shared_gc_info.gc_id(), cit.size_of_instances_in_words(), Ticks::now());
       cit.iterate(&event_sender);
     }
   }
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcTrace.hpp
--- a/src/share/vm/gc_implementation/shared/gcTrace.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/gcTrace.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -27,6 +27,7 @@
 
 #include "gc_interface/gcCause.hpp"
 #include "gc_interface/gcName.hpp"
+#include "gc_implementation/shared/gcId.hpp"
 #include "gc_implementation/shared/gcWhen.hpp"
 #include "gc_implementation/shared/copyFailedInfo.hpp"
 #include "memory/allocation.hpp"
@@ -38,7 +39,6 @@
 #include "utilities/macros.hpp"
 #include "utilities/ticks.hpp"
 
-typedef uint GCId;
 
 class EvacuationInfo;
 class GCHeapSummary;
@@ -50,11 +50,8 @@
 class BoolObjectClosure;
 
 class SharedGCInfo VALUE_OBJ_CLASS_SPEC {
- public:
-  static const GCId UNSET_GCID = (GCId)-1;
-
  private:
-  GCId _id;
+  GCId _gc_id;
   GCName _name;
   GCCause::Cause _cause;
   Ticks     _start_timestamp;
@@ -64,7 +61,7 @@
 
  public:
   SharedGCInfo(GCName name) :
-    _id(UNSET_GCID),
+    _gc_id(GCId::undefined()),
     _name(name),
     _cause(GCCause::_last_gc_cause),
     _start_timestamp(),
@@ -73,8 +70,8 @@
     _longest_pause() {
   }
 
-  void set_id(GCId id) { _id = id; }
-  GCId id() const { return _id; }
+  void set_gc_id(GCId gc_id) { _gc_id = gc_id; }
+  const GCId& gc_id() const { return _gc_id; }
 
   void set_start_timestamp(const Ticks& timestamp) { _start_timestamp = timestamp; }
   const Ticks start_timestamp() const { return _start_timestamp; }
@@ -131,10 +128,11 @@
   void report_gc_reference_stats(const ReferenceProcessorStats& rp) const;
   void report_object_count_after_gc(BoolObjectClosure* object_filter) NOT_SERVICES_RETURN;
   bool has_reported_gc_start() const;
+  const GCId& gc_id() { return _shared_gc_info.gc_id(); }
 
  protected:
   GCTracer(GCName name) : _shared_gc_info(name) {}
-  virtual void report_gc_start_impl(GCCause::Cause cause, const Ticks& timestamp);
+  void report_gc_start_impl(GCCause::Cause cause, const Ticks& timestamp);
   virtual void report_gc_end_impl(const Ticks& timestamp, TimePartitions* time_partitions);
 
  private:
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcTraceSend.cpp
--- a/src/share/vm/gc_implementation/shared/gcTraceSend.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/gcTraceSend.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -43,7 +43,7 @@
 void GCTracer::send_garbage_collection_event() const {
   EventGCGarbageCollection event(UNTIMED);
   if (event.should_commit()) {
-    event.set_gcId(_shared_gc_info.id());
+    event.set_gcId(_shared_gc_info.gc_id().id());
     event.set_name(_shared_gc_info.name());
     event.set_cause((u2) _shared_gc_info.cause());
     event.set_sumOfPauses(_shared_gc_info.sum_of_pauses());
@@ -57,7 +57,7 @@
 void GCTracer::send_reference_stats_event(ReferenceType type, size_t count) const {
   EventGCReferenceStatistics e;
   if (e.should_commit()) {
-      e.set_gcId(_shared_gc_info.id());
+      e.set_gcId(_shared_gc_info.gc_id().id());
       e.set_type((u1)type);
       e.set_count(count);
       e.commit();
@@ -68,7 +68,7 @@
                                                       const MetaspaceChunkFreeListSummary& summary) const {
   EventMetaspaceChunkFreeListSummary e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_when(when);
     e.set_metadataType(mdtype);
 
@@ -91,7 +91,7 @@
 void ParallelOldTracer::send_parallel_old_event() const {
   EventGCParallelOld e(UNTIMED);
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_densePrefix((TraceAddress)_parallel_old_gc_info.dense_prefix());
     e.set_starttime(_shared_gc_info.start_timestamp());
     e.set_endtime(_shared_gc_info.end_timestamp());
@@ -102,7 +102,7 @@
 void YoungGCTracer::send_young_gc_event() const {
   EventGCYoungGarbageCollection e(UNTIMED);
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_tenuringThreshold(_tenuring_threshold);
     e.set_starttime(_shared_gc_info.start_timestamp());
     e.set_endtime(_shared_gc_info.end_timestamp());
@@ -113,7 +113,7 @@
 void OldGCTracer::send_old_gc_event() const {
   EventGCOldGarbageCollection e(UNTIMED);
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_starttime(_shared_gc_info.start_timestamp());
     e.set_endtime(_shared_gc_info.end_timestamp());
     e.commit();
@@ -132,7 +132,7 @@
 void YoungGCTracer::send_promotion_failed_event(const PromotionFailedInfo& pf_info) const {
   EventPromotionFailed e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_data(to_trace_struct(pf_info));
     e.set_thread(pf_info.thread()->thread_id());
     e.commit();
@@ -143,7 +143,7 @@
 void OldGCTracer::send_concurrent_mode_failure_event() {
   EventConcurrentModeFailure e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.commit();
   }
 }
@@ -152,7 +152,7 @@
 void G1NewTracer::send_g1_young_gc_event() {
   EventGCG1GarbageCollection e(UNTIMED);
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_type(_g1_young_gc_info.type());
     e.set_starttime(_shared_gc_info.start_timestamp());
     e.set_endtime(_shared_gc_info.end_timestamp());
@@ -163,7 +163,7 @@
 void G1NewTracer::send_evacuation_info_event(EvacuationInfo* info) {
   EventEvacuationInfo e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_cSetRegions(info->collectionset_regions());
     e.set_cSetUsedBefore(info->collectionset_used_before());
     e.set_cSetUsedAfter(info->collectionset_used_after());
@@ -179,7 +179,7 @@
 void G1NewTracer::send_evacuation_failed_event(const EvacuationFailedInfo& ef_info) const {
   EventEvacuationFailed e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_data(to_trace_struct(ef_info));
     e.commit();
   }
@@ -206,17 +206,17 @@
 }
 
 class GCHeapSummaryEventSender : public GCHeapSummaryVisitor {
-  GCId _id;
+  GCId _gc_id;
   GCWhen::Type _when;
  public:
-  GCHeapSummaryEventSender(GCId id, GCWhen::Type when) : _id(id), _when(when) {}
+  GCHeapSummaryEventSender(GCId gc_id, GCWhen::Type when) : _gc_id(gc_id), _when(when) {}
 
   void visit(const GCHeapSummary* heap_summary) const {
     const VirtualSpaceSummary& heap_space = heap_summary->heap();
 
     EventGCHeapSummary e;
     if (e.should_commit()) {
-      e.set_gcId(_id);
+      e.set_gcId(_gc_id.id());
       e.set_when((u1)_when);
       e.set_heapSpace(to_trace_struct(heap_space));
       e.set_heapUsed(heap_summary->used());
@@ -236,7 +236,7 @@
 
     EventPSHeapSummary e;
     if (e.should_commit()) {
-      e.set_gcId(_id);
+      e.set_gcId(_gc_id.id());
       e.set_when((u1)_when);
 
       e.set_oldSpace(to_trace_struct(ps_heap_summary->old()));
@@ -251,7 +251,7 @@
 };
 
 void GCTracer::send_gc_heap_summary_event(GCWhen::Type when, const GCHeapSummary& heap_summary) const {
-  GCHeapSummaryEventSender visitor(_shared_gc_info.id(), when);
+  GCHeapSummaryEventSender visitor(_shared_gc_info.gc_id(), when);
   heap_summary.accept(&visitor);
 }
 
@@ -268,7 +268,7 @@
 void GCTracer::send_meta_space_summary_event(GCWhen::Type when, const MetaspaceSummary& meta_space_summary) const {
   EventMetaspaceSummary e;
   if (e.should_commit()) {
-    e.set_gcId(_shared_gc_info.id());
+    e.set_gcId(_shared_gc_info.gc_id().id());
     e.set_when((u1) when);
     e.set_gcThreshold(meta_space_summary.capacity_until_GC());
     e.set_metaspace(to_trace_struct(meta_space_summary.meta_space()));
@@ -287,7 +287,7 @@
   void send_phase(PausePhase* pause) {
     T event(UNTIMED);
     if (event.should_commit()) {
-      event.set_gcId(_gc_id);
+      event.set_gcId(_gc_id.id());
       event.set_name(pause->name());
       event.set_starttime(pause->start());
       event.set_endtime(pause->end());
@@ -311,7 +311,7 @@
 };
 
 void GCTracer::send_phase_events(TimePartitions* time_partitions) const {
-  PhaseSender phase_reporter(_shared_gc_info.id());
+  PhaseSender phase_reporter(_shared_gc_info.gc_id());
 
   TimePartitionPhasesIterator iter(time_partitions);
   while (iter.has_next()) {
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcTraceTime.cpp
--- a/src/share/vm/gc_implementation/shared/gcTraceTime.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/gcTraceTime.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
+#include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
 #include "runtime/globals.hpp"
 #include "runtime/os.hpp"
@@ -34,7 +35,7 @@
 #include "utilities/ticks.inline.hpp"
 
 
-GCTraceTime::GCTraceTime(const char* title, bool doit, bool print_cr, GCTimer* timer) :
+GCTraceTime::GCTraceTime(const char* title, bool doit, bool print_cr, GCTimer* timer, GCId gc_id) :
     _title(title), _doit(doit), _print_cr(print_cr), _timer(timer), _start_counter() {
   if (_doit || _timer != NULL) {
     _start_counter.stamp();
@@ -52,6 +53,9 @@
       gclog_or_tty->stamp();
       gclog_or_tty->print(": ");
     }
+    if (PrintGCID) {
+      gclog_or_tty->print("#%u: ", gc_id.id());
+    }
     gclog_or_tty->print("[%s", title);
     gclog_or_tty->flush();
   }
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/gcTraceTime.hpp
--- a/src/share/vm/gc_implementation/shared/gcTraceTime.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/gcTraceTime.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_GCTRACETIME_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_GCTRACETIME_HPP
 
+#include "gc_implementation/shared/gcTrace.hpp"
 #include "prims/jni_md.h"
 #include "utilities/ticks.hpp"
 
@@ -38,7 +39,7 @@
   Ticks _start_counter;
 
  public:
-  GCTraceTime(const char* title, bool doit, bool print_cr, GCTimer* timer);
+  GCTraceTime(const char* title, bool doit, bool print_cr, GCTimer* timer, GCId gc_id);
   ~GCTraceTime();
 };
 
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_implementation/shared/objectCountEventSender.cpp
--- a/src/share/vm/gc_implementation/shared/objectCountEventSender.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_implementation/shared/objectCountEventSender.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -24,6 +24,7 @@
 
 
 #include "precompiled.hpp"
+#include "gc_implementation/shared/gcId.hpp"
 #include "gc_implementation/shared/objectCountEventSender.hpp"
 #include "memory/heapInspection.hpp"
 #include "trace/tracing.hpp"
@@ -38,7 +39,7 @@
          "Only call this method if the event is enabled");
 
   EventObjectCountAfterGC event(UNTIMED);
-  event.set_gcId(gc_id);
+  event.set_gcId(gc_id.id());
   event.set_class(entry->klass());
   event.set_count(entry->count());
   event.set_totalSize(entry->words() * BytesPerWord);
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/gc_interface/collectedHeap.cpp
--- a/src/share/vm/gc_interface/collectedHeap.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/gc_interface/collectedHeap.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -558,13 +558,13 @@
 
 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
   if (HeapDumpBeforeFullGC) {
-    GCTraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, timer);
+    GCTraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, timer, GCId::create());
     // We are doing a "major" collection and a heap dump before
     // major collection has been requested.
     HeapDumper::dump_heap();
   }
   if (PrintClassHistogramBeforeFullGC) {
-    GCTraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, timer);
+    GCTraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, timer, GCId::create());
     VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */);
     inspector.doit();
   }
@@ -572,11 +572,11 @@
 
 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
   if (HeapDumpAfterFullGC) {
-    GCTraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, timer);
+    GCTraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, timer, GCId::create());
     HeapDumper::dump_heap();
   }
   if (PrintClassHistogramAfterFullGC) {
-    GCTraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, timer);
+    GCTraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, timer, GCId::create());
     VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */);
     inspector.doit();
   }
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/memory/defNewGeneration.cpp
--- a/src/share/vm/memory/defNewGeneration.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/memory/defNewGeneration.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -584,7 +584,7 @@
 
   init_assuming_no_promotion_failure();
 
-  GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
+  GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, gc_tracer.gc_id());
   // Capture heap used before collection (for printing).
   size_t gch_prev_used = gch->used();
 
@@ -642,7 +642,7 @@
   rp->setup_policy(clear_all_soft_refs);
   const ReferenceProcessorStats& stats =
   rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
-                                    NULL, _gc_timer);
+                                    NULL, _gc_timer, gc_tracer.gc_id());
   gc_tracer.report_gc_reference_stats(stats);
 
   if (!_promotion_failed) {
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/memory/genCollectedHeap.cpp
--- a/src/share/vm/memory/genCollectedHeap.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/memory/genCollectedHeap.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -28,6 +28,7 @@
 #include "classfile/vmSymbols.hpp"
 #include "code/icBuffer.hpp"
 #include "gc_implementation/shared/collectorCounters.hpp"
+#include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
 #include "gc_implementation/shared/vmGCOperations.hpp"
 #include "gc_interface/collectedHeap.inline.hpp"
@@ -385,7 +386,9 @@
     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
-    GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
+    // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
+    // so we can assume here that the next GC id is what we want.
+    GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 
     gc_prologue(complete);
     increment_total_collections(complete);
@@ -418,7 +421,9 @@
         }
         // Timer for individual generations. Last argument is false: no CR
         // FIXME: We should try to start the timing earlier to cover more of the GC pause
-        GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL);
+        // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
+        // so we can assume here that the next GC id is what we want.
+        GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
         TraceCollectorStats tcs(_gens[i]->counters());
         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/memory/genMarkSweep.cpp
--- a/src/share/vm/memory/genMarkSweep.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/memory/genMarkSweep.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -69,7 +69,7 @@
   _ref_processor = rp;
   rp->setup_policy(clear_all_softrefs);
 
-  GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
+  GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, _gc_tracer->gc_id());
 
   gch->trace_heap_before_gc(_gc_tracer);
 
@@ -193,7 +193,7 @@
 void GenMarkSweep::mark_sweep_phase1(int level,
                                   bool clear_all_softrefs) {
   // Recursively traverse all live objects and mark them
-  GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace(" 1");
 
   GenCollectedHeap* gch = GenCollectedHeap::heap();
@@ -222,7 +222,7 @@
     ref_processor()->setup_policy(clear_all_softrefs);
     const ReferenceProcessorStats& stats =
       ref_processor()->process_discovered_references(
-        &is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer);
+        &is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer, _gc_tracer->gc_id());
     gc_tracer()->report_gc_reference_stats(stats);
   }
 
@@ -264,7 +264,7 @@
 
   GenCollectedHeap* gch = GenCollectedHeap::heap();
 
-  GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("2");
 
   gch->prepare_for_compaction();
@@ -281,7 +281,7 @@
   GenCollectedHeap* gch = GenCollectedHeap::heap();
 
   // Adjust the pointers to reflect the new locations
-  GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("3");
 
   // Need new claim bits for the pointer adjustment tracing.
@@ -336,7 +336,7 @@
   // to use a higher index (saved from phase2) when verifying perm_gen.
   GenCollectedHeap* gch = GenCollectedHeap::heap();
 
-  GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer);
+  GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer, _gc_tracer->gc_id());
   trace("4");
 
   GenCompactClosure blk;
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/memory/referenceProcessor.cpp
--- a/src/share/vm/memory/referenceProcessor.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/memory/referenceProcessor.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -190,7 +190,8 @@
   OopClosure*                  keep_alive,
   VoidClosure*                 complete_gc,
   AbstractRefProcTaskExecutor* task_executor,
-  GCTimer*                     gc_timer) {
+  GCTimer*                     gc_timer,
+  GCId                         gc_id) {
   NOT_PRODUCT(verify_ok_to_handle_reflists());
 
   assert(!enqueuing_is_done(), "If here enqueuing should not be complete");
@@ -212,7 +213,7 @@
   // Soft references
   size_t soft_count = 0;
   {
-    GCTraceTime tt("SoftReference", trace_time, false, gc_timer);
+    GCTraceTime tt("SoftReference", trace_time, false, gc_timer, gc_id);
     soft_count =
       process_discovered_reflist(_discoveredSoftRefs, _current_soft_ref_policy, true,
                                  is_alive, keep_alive, complete_gc, task_executor);
@@ -223,7 +224,7 @@
   // Weak references
   size_t weak_count = 0;
   {
-    GCTraceTime tt("WeakReference", trace_time, false, gc_timer);
+    GCTraceTime tt("WeakReference", trace_time, false, gc_timer, gc_id);
     weak_count =
       process_discovered_reflist(_discoveredWeakRefs, NULL, true,
                                  is_alive, keep_alive, complete_gc, task_executor);
@@ -232,7 +233,7 @@
   // Final references
   size_t final_count = 0;
   {
-    GCTraceTime tt("FinalReference", trace_time, false, gc_timer);
+    GCTraceTime tt("FinalReference", trace_time, false, gc_timer, gc_id);
     final_count =
       process_discovered_reflist(_discoveredFinalRefs, NULL, false,
                                  is_alive, keep_alive, complete_gc, task_executor);
@@ -241,7 +242,7 @@
   // Phantom references
   size_t phantom_count = 0;
   {
-    GCTraceTime tt("PhantomReference", trace_time, false, gc_timer);
+    GCTraceTime tt("PhantomReference", trace_time, false, gc_timer, gc_id);
     phantom_count =
       process_discovered_reflist(_discoveredPhantomRefs, NULL, false,
                                  is_alive, keep_alive, complete_gc, task_executor);
@@ -253,7 +254,7 @@
   // thus use JNI weak references to circumvent the phantom references and
   // resurrect a "post-mortem" object.
   {
-    GCTraceTime tt("JNI Weak Reference", trace_time, false, gc_timer);
+    GCTraceTime tt("JNI Weak Reference", trace_time, false, gc_timer, gc_id);
     if (task_executor != NULL) {
       task_executor->set_single_threaded_mode();
     }
@@ -1251,14 +1252,15 @@
   OopClosure* keep_alive,
   VoidClosure* complete_gc,
   YieldClosure* yield,
-  GCTimer* gc_timer) {
+  GCTimer* gc_timer,
+  GCId     gc_id) {
 
   NOT_PRODUCT(verify_ok_to_handle_reflists());
 
   // Soft references
   {
     GCTraceTime tt("Preclean SoftReferences", PrintGCDetails && PrintReferenceGC,
-              false, gc_timer);
+              false, gc_timer, gc_id);
     for (uint i = 0; i < _max_num_q; i++) {
       if (yield->should_return()) {
         return;
@@ -1271,7 +1273,7 @@
   // Weak references
   {
     GCTraceTime tt("Preclean WeakReferences", PrintGCDetails && PrintReferenceGC,
-              false, gc_timer);
+              false, gc_timer, gc_id);
     for (uint i = 0; i < _max_num_q; i++) {
       if (yield->should_return()) {
         return;
@@ -1284,7 +1286,7 @@
   // Final references
   {
     GCTraceTime tt("Preclean FinalReferences", PrintGCDetails && PrintReferenceGC,
-              false, gc_timer);
+              false, gc_timer, gc_id);
     for (uint i = 0; i < _max_num_q; i++) {
       if (yield->should_return()) {
         return;
@@ -1297,7 +1299,7 @@
   // Phantom references
   {
     GCTraceTime tt("Preclean PhantomReferences", PrintGCDetails && PrintReferenceGC,
-              false, gc_timer);
+              false, gc_timer, gc_id);
     for (uint i = 0; i < _max_num_q; i++) {
       if (yield->should_return()) {
         return;
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/memory/referenceProcessor.hpp
--- a/src/share/vm/memory/referenceProcessor.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/memory/referenceProcessor.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
 #define SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
 
+#include "gc_implementation/shared/gcTrace.hpp"
 #include "memory/referencePolicy.hpp"
 #include "memory/referenceProcessorStats.hpp"
 #include "memory/referenceType.hpp"
@@ -349,7 +350,8 @@
                                       OopClosure*        keep_alive,
                                       VoidClosure*       complete_gc,
                                       YieldClosure*      yield,
-                                      GCTimer*           gc_timer);
+                                      GCTimer*           gc_timer,
+                                      GCId               gc_id);
 
   // Delete entries in the discovered lists that have
   // either a null referent or are not active. Such
@@ -480,7 +482,8 @@
                                 OopClosure*                  keep_alive,
                                 VoidClosure*                 complete_gc,
                                 AbstractRefProcTaskExecutor* task_executor,
-                                GCTimer *gc_timer);
+                                GCTimer *gc_timer,
+                                GCId    gc_id);
 
   // Enqueue references at end of GC (called by the garbage collector)
   bool enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor = NULL);
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/runtime/globals.hpp
--- a/src/share/vm/runtime/globals.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/runtime/globals.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -2287,6 +2287,9 @@
   manageable(bool, PrintGCTimeStamps, false,                                \
           "Print timestamps at garbage collection")                         \
                                                                             \
+  manageable(bool, PrintGCID, false,                                        \
+          "Print an identifier for each garbage collection")                \
+                                                                            \
   product(bool, PrintGCTaskTimeStamps, false,                               \
           "Print timestamps for individual gc worker thread tasks")         \
                                                                             \
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/utilities/ostream.cpp
--- a/src/share/vm/utilities/ostream.cpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/utilities/ostream.cpp	Thu Jun 19 13:31:14 2014 +0200
@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "compiler/compileLog.hpp"
+#include "gc_implementation/shared/gcId.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/arguments.hpp"
 #include "utilities/defaultStream.hpp"
@@ -240,6 +241,14 @@
   return;
 }
 
+void outputStream::gclog_stamp(const GCId& gc_id) {
+  date_stamp(PrintGCDateStamps);
+  stamp(PrintGCTimeStamps);
+  if (PrintGCID) {
+    print("#%u: ", gc_id.id());
+  }
+}
+
 outputStream& outputStream::indent() {
   while (_position < _indentation) sp();
   return *this;
diff -r 5d855d021755 -r 0982ec23da03 src/share/vm/utilities/ostream.hpp
--- a/src/share/vm/utilities/ostream.hpp	Wed Jun 25 15:51:15 2014 -0700
+++ b/src/share/vm/utilities/ostream.hpp	Thu Jun 19 13:31:14 2014 +0200
@@ -28,6 +28,7 @@
 #include "memory/allocation.hpp"
 #include "runtime/timer.hpp"
 
+class GCId;
 DEBUG_ONLY(class ResourceMark;)
 
 // Output streams for printing
@@ -107,6 +108,7 @@
    void date_stamp(bool guard) {
      date_stamp(guard, "", ": ");
    }
+   void gclog_stamp(const GCId& gc_id);
 
    // portable printing of 64 bit integers
    void print_jlong(jlong value);
diff -r 5d855d021755 -r 0982ec23da03 test/gc/logging/TestGCId.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/gc/logging/TestGCId.java	Thu Jun 19 13:31:14 2014 +0200
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test TestGCId
+ * @bug 8043607
+ * @summary Ensure that the GCId is logged
+ * @key gc
+ * @library /testlibrary
+ */
+
+import com.oracle.java.testlibrary.ProcessTools;
+import com.oracle.java.testlibrary.OutputAnalyzer;
+
+public class TestGCId {
+  public static void main(String[] args) throws Exception {
+    testGCId("UseParallelGC", "PrintGC");
+    testGCId("UseParallelGC", "PrintGCDetails");
+
+    testGCId("UseG1GC", "PrintGC");
+    testGCId("UseG1GC", "PrintGCDetails");
+
+    testGCId("UseConcMarkSweepGC", "PrintGC");
+    testGCId("UseConcMarkSweepGC", "PrintGCDetails");
+
+    testGCId("UseSerialGC", "PrintGC");
+    testGCId("UseSerialGC", "PrintGCDetails");
+  }
+
+  private static void verifyContainsGCIDs(OutputAnalyzer output) {
+    output.shouldMatch("^#0: \\[");
+    output.shouldMatch("^#1: \\[");
+    output.shouldHaveExitValue(0);
+  }
+
+  private static void verifyContainsNoGCIDs(OutputAnalyzer output) {
+    output.shouldNotMatch("^#[0-9]+: \\[");
+    output.shouldHaveExitValue(0);
+  }
+
+  private static void testGCId(String gcFlag, String logFlag) throws Exception {
+    // GCID logging enabled
+    ProcessBuilder pb_enabled =
+      ProcessTools.createJavaProcessBuilder("-XX:+" + gcFlag, "-XX:+" + logFlag, "-Xmx10M", "-XX:+PrintGCID", GCTest.class.getName());
+    verifyContainsGCIDs(new OutputAnalyzer(pb_enabled.start()));
+
+    // GCID logging disabled
+    ProcessBuilder pb_disabled =
+      ProcessTools.createJavaProcessBuilder("-XX:+" + gcFlag, "-XX:+" + logFlag, "-Xmx10M", "-XX:-PrintGCID", GCTest.class.getName());
+    verifyContainsNoGCIDs(new OutputAnalyzer(pb_disabled.start()));
+
+    // GCID logging default
+    ProcessBuilder pb_default =
+      ProcessTools.createJavaProcessBuilder("-XX:+" + gcFlag, "-XX:+" + logFlag, "-Xmx10M", GCTest.class.getName());
+    verifyContainsGCIDs(new OutputAnalyzer(pb_default.start()));
+  }
+
+  static class GCTest {
+    private static byte[] garbage;
+    public static void main(String [] args) {
+      System.out.println("Creating garbage");
+      // create 128MB of garbage. This should result in at least one GC
+      for (int i = 0; i < 1024; i++) {
+        garbage = new byte[128 * 1024];
+      }
+      // do a system gc to get one more gc
+      System.gc();
+      System.out.println("Done");
+    }
+  }
+}