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Posted to dev@lucenenet.apache.org by "Digy (JIRA)" <ji...@apache.org> on 2011/08/27 20:54:37 UTC
[Lucene.Net] [jira] [Updated] (LUCENENET-358) CloseableThreadLocal memory leak
in LocalDataStoreSlot (with workaround)
[ https://issues.apache.org/jira/browse/LUCENENET-358?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Digy updated LUCENENET-358:
---------------------------
Attachment: TestMemLeakage.zip
TestMemLeakage.zip shows that bug.
> CloseableThreadLocal memory leak in LocalDataStoreSlot (with workaround)
> -------------------------------------------------------------------------
>
> Key: LUCENENET-358
> URL: https://issues.apache.org/jira/browse/LUCENENET-358
> Project: Lucene.Net
> Issue Type: Bug
> Environment: Microsoft WIndows Server 2008 Enterprise x64. SP2.
> .NET Framework 4.0
> Reporter: Rezgar Cadro
> Assignee: Digy
> Priority: Critical
> Labels: "memory, CloseableThreadLocal, LocalDataStoreSlot, leak"
> Attachments: CloseableThreadLocal MemoryLeak.patch, CloseableThreadLocal.diff, CloseableThreadLocal.diff, CloseableThreadLocal.patch, TestMemLeakage.zip
>
>
> Recently we have been suffering from a severe memory leak when executing intense open/close operations on IndexSearcher and IndexModifier.
> Memory profiling showed that memory is being held by LocalDataStore[] objects.
> After some digging, the root of the problem has been found in CloseableThreadLocal class:
> private System.LocalDataStoreSlot t = System.Threading.Thread.AllocateDataSlot();
> What we see is that every instantiated object of CloseableThreadLocal causes new data slot allocation performed for every thread.
> Thread.AllocateDataSlot() does not simply allocate a new slot, replacing an old one, but enlarging an existing buffer in-thread, appending data to the end of internal LocalDataStore[] collection, which causes a severe memory leak .
> As long as "t" variable is instantiated on every object creation, and (in current class implementation) every object is used by a single thread, replacing "private System.LocalDataStoreSlot t = System.Threading.Thread.AllocateDataSlot();" with simple "private object dataSlot;" and removing "hardRefs" Dictionary solves the problem and prevents memory leak.
> We have tried to implement the expected behavior by using [ThreadStatic] attribute instead of LocalDataStoreSlot, but the attempt failed because of unexpected exceptions being thrown.
> Patch can be found at Lucene.Net repository under
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