Bug ID: JDK-6912018 CMS: guarantee(head() != 0,"The head of the list cannot be NULL")

Type: Bug
Component: hotspot
Sub-Component: gc
Affected Version: 6u1,6u5-rev,6u16,6u18,7

Priority: P3
Status: Closed
Resolution: Fixed
OS:
generic,linux_redhat_5.2,solaris,solaris_10 generic,linux_redhat_5.2,solaris,solaris_10
CPU: generic,x86,sparc

Submitted: 2009-12-19
Updated: 2011-03-08
Resolved: 2011-03-08

Other	JDK 6	JDK 7	Other
1.4.2_31,hs16.3Fixed	6u20-revFixed	7Fixed	hs16.3Fixed

Unexpected Error
------------------------------------------------------------------------------
Internal Error at binaryTreeDictionary.cpp:258, pid=2490, tid=8
Error: guarantee(head() != 0,"The head of the list cannot be NULL")

EVALUATION http://hg.openjdk.java.net/jdk7/hotspot/hotspot/rev/05b775309e59
09-01-2010
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/05b775309e59
07-01-2010
SUGGESTED FIX The updated fix (assertion check added). arches% hg diff src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp --- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp @@ -3075,7 +3075,18 @@ void CompactibleFreeListSpace:: par_get_ if (rem > 0 && rem < MinChunkSize) { n--; rem += word_sz; } - assert((ssize_t)n >= 1, "Control point invariant"); + // Note that at this point we may have n == 0. + assert((ssize_t)n >= 0, "Control point invariant"); + + // If n is 0, the chunk fc that was found is not large + // enough to leave a viable remainder. We are unable to + // allocate even one block. Return fc to the + // dictionary and return, leaving "fl" empty. + if (n == 0) { + returnChunkToDictionary(fc); + return; + } + // First return the remainder, if any. // Note that we hold the lock until we decide if we're going to give // back the remainder to the dictionary, since a concurrent allocation
29-12-2009
EVALUATION The assertion failure exposed in additional testing indicated that the number of blocks being taken in par_get_chunk_of_blocks() was incorrectly reduced to 0. A fix for that case was made and testing of that fix for the failed guarantee reported here is in progress.
22-12-2009
SUGGESTED FIX diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp--- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp @@ -2731,6 +2731,14 @@ par_get_chunk_of_blocks(size_t word_sz, if (rem > 0 && rem < MinChunkSize) { n--; rem += word_sz; } + // If n is 0, there chunk fc that was found is not large + // enough to leave a viable remainder. Return fc to the + // dictionary and return. + if (n == 0) { + returnChunkToDictionary(fc); + return; + } + // First return the remainder, if any. // Note that we hold the lock until we decide if we're going to give // back the remainder to the dictionary, since a contending allocator
22-12-2009

Duplicate :	JDK-6538488 - CMS: crashed in removeChunkReplaceIfNeeded
Duplicate :	JDK-6901609 - CMS crash in GCTaskThread BinaryTreeDictionary::getChunkFromTree
Relates :	JDK-6916968 - CMS: freeList.cpp:304 assert(_allocation_stats.prevSweep() + ..., "Conservation Principle")
Relates :	JDK-6565513 - CMS: assert at blockOffsetTable.cpp:39: assert(left_blk_size > 0,"Should be positive")