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7129271: G1: Interference from multiple threads in PrintGC/PrintGCDetails output

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During an initial mark pause, signal the Concurrent Mark thread after the pause output from PrintGC/PrintGCDetails is complete.

Reviewed-by: tonyp, brutisso
This commit is contained in:
John Cuthbertson 2012-01-17 10:21:43 -08:00
parent c9eb103b7f
commit 43a30ad483
1 changed files with 45 additions and 21 deletions
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44
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
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@ -3557,7 +3557,6 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
verify_region_sets_optional();
verify_dirty_young_regions();
{
// This call will decide whether this pause is an initial-mark
// pause. If it is, during_initial_mark_pause() will return true
// for the duration of this pause.
@ -3570,6 +3569,13 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
// We also do not allow mixed GCs during marking.
assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
// Record whether this pause is an initial mark. When the current
// thread has completed its logging output and it's safe to signal
// the CM thread, the flag's value in the policy has been reset.
bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
// Inner scope for scope based logging, timers, and stats collection
{
char verbose_str[128];
sprintf(verbose_str, "GC pause ");
if (g1_policy()->gcs_are_young()) {
@ -3625,7 +3631,6 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
Universe::verify(/* allow dirty */ false,
/* silent */ false,
/* option */ VerifyOption_G1UsePrevMarking);
}
COMPILER2_PRESENT(DerivedPointerTable::clear());
@ -3779,14 +3784,9 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
if (g1_policy()->during_initial_mark_pause()) {
concurrent_mark()->checkpointRootsInitialPost();
set_marking_started();
// CAUTION: after the doConcurrentMark() call below,
// the concurrent marking thread(s) could be running
// concurrently with us. Make sure that anything after
// this point does not assume that we are the only GC thread
// running. Note: of course, the actual marking work will
// not start until the safepoint itself is released in
// ConcurrentGCThread::safepoint_desynchronize().
doConcurrentMark();
// Note that we don't actually trigger the CM thread at
// this point. We do that later when we're sure that
// the current thread has completed its logging output.
}
allocate_dummy_regions();
@ -3896,6 +3896,15 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
}
}
// The closing of the inner scope, immediately above, will complete
// the PrintGC logging output. The record_collection_pause_end() call
// above will complete the logging output of PrintGCDetails.
//
// It is not yet to safe, however, to tell the concurrent mark to
// start as we have some optional output below. We don't want the
// output from the concurrent mark thread interfering with this
// logging output either.
_hrs.verify_optional();
verify_region_sets_optional();
@ -3913,6 +3922,21 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
g1_rem_set()->print_summary_info();
}
// It should now be safe to tell the concurrent mark thread to start
// without its logging output interfering with the logging output
// that came from the pause.
if (should_start_conc_mark) {
// CAUTION: after the doConcurrentMark() call below,
// the concurrent marking thread(s) could be running
// concurrently with us. Make sure that anything after
// this point does not assume that we are the only GC thread
// running. Note: of course, the actual marking work will
// not start until the safepoint itself is released in
// ConcurrentGCThread::safepoint_desynchronize().
doConcurrentMark();
}
return true;
}