Mercurial > hg > graal-compiler
changeset 1840:4e0094bc41fa
6983311: G1: LoopTest hangs when run with -XX:+ExplicitInvokesConcurrent
Summary: Clear the concurrent marking "in progress" flag while the FullGCCount_lock is held. This avoids a race that can cause back to back System.gc() calls, when ExplicitGCInvokesConcurrent is enabled, to fail to initiate a marking cycle causing the requesting thread to hang.
Reviewed-by: tonyp, ysr
| author | johnc |
|---|---|
| date | Fri, 01 Oct 2010 18:23:16 -0700 |
| parents | 8f6f7587d292 |
| children | 32a1f7bf0c21 |
| files | src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp |
| diffstat | 3 files changed, 14 insertions(+), 5 deletions(-) [+] |
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--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp Thu Sep 30 12:15:13 2010 -0700 +++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp Fri Oct 01 18:23:16 2010 -0700 @@ -303,9 +303,10 @@ } void ConcurrentMarkThread::sleepBeforeNextCycle() { - clear_in_progress(); // We join here because we don't want to do the "shouldConcurrentMark()" // below while the world is otherwise stopped. + assert(!in_progress(), "should have been cleared"); + MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); while (!started()) { CGC_lock->wait(Mutex::_no_safepoint_check_flag);
--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp Thu Sep 30 12:15:13 2010 -0700 +++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp Fri Oct 01 18:23:16 2010 -0700 @@ -69,12 +69,12 @@ ConcurrentMark* cm() { return _cm; } - void set_started() { _started = true; } - void clear_started() { _started = false; } + void set_started() { assert(!_in_progress, "cycle in progress"); _started = true; } + void clear_started() { assert(_in_progress, "must be starting a cycle"); _started = false; } bool started() { return _started; } - void set_in_progress() { _in_progress = true; } - void clear_in_progress() { _in_progress = false; } + void set_in_progress() { assert(_started, "must be starting a cycle"); _in_progress = true; } + void clear_in_progress() { assert(!_started, "must not be starting a new cycle"); _in_progress = false; } bool in_progress() { return _in_progress; } // This flag returns true from the moment a marking cycle is
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Thu Sep 30 12:15:13 2010 -0700 +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp Fri Oct 01 18:23:16 2010 -0700 @@ -1785,6 +1785,14 @@ _full_collections_completed += 1; + // We need to clear the "in_progress" flag in the CM thread before + // we wake up any waiters (especially when ExplicitInvokesConcurrent + // is set) so that if a waiter requests another System.gc() it doesn't + // incorrectly see that a marking cyle is still in progress. + if (outer) { + _cmThread->clear_in_progress(); + } + // This notify_all() will ensure that a thread that called // System.gc() with (with ExplicitGCInvokesConcurrent set or not) // and it's waiting for a full GC to finish will be woken up. It is