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6987703: iCMS: Intermittent hang with gc/gctests/CallGC/CallGC01 and +ExplicitGCInvokesConcurrent

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Count enable_icms() and disable_icms() events so as to prevent inteference between concurrent calls, which can cause the iCMS thread to be left stranded in icms_wait() with an unserviced request and no young allocations to unwedge it.

Reviewed-by: jcoomes, poonam
This commit is contained in:
Y. Srinivas Ramakrishna 2011-03-14 21:52:24 -07:00
parent edb9e105eb
commit a3de65241c
5 changed files with 44 additions and 20 deletions
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14
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2005, 2011, 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
@ -192,14 +192,18 @@ void VM_GenCollectFullConcurrent::doit() {
"total_collections() should be monotonically increasing");
MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
assert(_full_gc_count_before <= gch->total_full_collections(), "Error");
if (gch->total_full_collections() == _full_gc_count_before) {
// Disable iCMS until the full collection is done.
// Disable iCMS until the full collection is done, and
// remember that we did so.
CMSCollector::disable_icms();
_disabled_icms = true;
// In case CMS thread was in icms_wait(), wake it up.
CMSCollector::start_icms();
// Nudge the CMS thread to start a concurrent collection.
CMSCollector::request_full_gc(_full_gc_count_before);
} else {
assert(_full_gc_count_before < gch->total_full_collections(), "Error");
FullGCCount_lock->notify_all(); // Inform the Java thread its work is done
}
}
@ -259,6 +263,8 @@ void VM_GenCollectFullConcurrent::doit_epilogue() {
FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
}
}
// Enable iCMS back.
CMSCollector::enable_icms();
// Enable iCMS back if we disabled it earlier.
if (_disabled_icms) {
CMSCollector::enable_icms();
}
}