hg: jdk7/hotspot-gc/hotspot: 6948538: CMS: BOT walkers can fall into object allocation and initialization cracks

[y.s.ramakrishna at oracle.com]

Changeset: be3f9c242c9d
Author:    ysr
Date:      2010-08-16 15:58 -0700
URL:       http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/be3f9c242c9d

6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam

! src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
! src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp
! src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
! src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp
! src/share/vm/gc_implementation/concurrentMarkSweep/freeChunk.hpp
! src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp
! src/share/vm/gc_implementation/includeDB_gc_concurrentMarkSweep
! src/share/vm/includeDB_core
! src/share/vm/memory/blockOffsetTable.cpp
! src/share/vm/memory/blockOffsetTable.hpp
! src/share/vm/memory/blockOffsetTable.inline.hpp
! src/share/vm/runtime/globals.hpp