RFR (S): 8014971: Minor code cleanup of the freelist management
bengt.rutisson at oracle.com
Wed May 22 06:07:52 UTC 2013
Thanks for the reviews, Jesper, Jon and Thomas!
Pushing this now.
Thomas, I removed the commented out line that you mentioned.
On 5/21/13 3:35 PM, Bengt Rutisson wrote:
> Hi all,
> While fixing 'JDK-7066063: CMS: "Conservation Principle" assert
> failed' I made some code cleanups in the code I was browsing. I didn't
> want to mix these changes in with the bug fix, so I'm submitting this
> review for those changes. Could I have a couple of reviews of this
> small cleanup?
> Here is what I did:
> - Removed the unused constructors for FreeList and AdaptiveFreeList
> - Removed unnecessary NULL check after call to global operator new.
> The new operator already checks the allocation and exits the VM if it
> - Removed unused old_end variable in
> - Fixed a possible bug in
> The last fix may require some explanation. In the constructor for
> CompactibleFreeListSpace() we set up the _indexedFreeListParLocks
> array. But we only set it up if ParallelGCThreads > 0, so if we are
> single threaded the locks are unintialized (not even NULL, just random
> values). In
> CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats() we
> use these locks but we don't check for ParallelGCThreads > 0. We only
> check the chunk size to see if there is a chance that the chunk may
> end up in the smaller buckets. This will fail if ParallelGCThreads = 0.
> This bug is benign since
> CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats() is
> only used when we grow or shrink the generation. This is always done
> with os::vm_allocation_granularity() which is larger than
> SmallForDictionary so we will never enter the dangerous code path.
> However, if someone in the future either increases the value of
> SmallForDictionary or uses a smaller alignment for the generation
> sizing we might hit this problem. So, I figured it is worth leaving
> the code but making sure that it works properly.
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