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6676175: BigApps crash JVM Client VM (build 10.0-b22, mixed mode, sharing) with SIGSEGV (0xb)

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Add test for biased locking epoch before walking own thread stack in case of rare race

Reviewed-by: phh, never
This commit is contained in:
Coleen Phillimore 2008-11-21 08:09:11 -08:00
parent 8db365aa80
commit 50a5499c50
1 changed files with 7 additions and 1 deletions
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8
hotspot/src/share/vm/runtime/biasedLocking.cpp
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@ -582,13 +582,19 @@ BiasedLocking::Condition BiasedLocking::revoke_and_rebias(Handle obj, bool attem
if (heuristics == HR_NOT_BIASED) { if (heuristics == HR_NOT_BIASED) {
return NOT_BIASED; return NOT_BIASED;
} else if (heuristics == HR_SINGLE_REVOKE) { } else if (heuristics == HR_SINGLE_REVOKE) {
if (mark->biased_locker() == THREAD) { Klass *k = Klass::cast(obj->klass());
markOop prototype_header = k->prototype_header();
if (mark->biased_locker() == THREAD &&
prototype_header->bias_epoch() == mark->bias_epoch()) {
// A thread is trying to revoke the bias of an object biased // A thread is trying to revoke the bias of an object biased
// toward it, again likely due to an identity hash code // toward it, again likely due to an identity hash code
// computation. We can again avoid a safepoint in this case // computation. We can again avoid a safepoint in this case
// since we are only going to walk our own stack. There are no // since we are only going to walk our own stack. There are no
// races with revocations occurring in other threads because we // races with revocations occurring in other threads because we
// reach no safepoints in the revocation path. // reach no safepoints in the revocation path.
// Also check the epoch because even if threads match, another thread
// can come in with a CAS to steal the bias of an object that has a
// stale epoch.
ResourceMark rm; ResourceMark rm;
if (TraceBiasedLocking) { if (TraceBiasedLocking) {
tty->print_cr("Revoking bias by walking my own stack:"); tty->print_cr("Revoking bias by walking my own stack:");