Hi, About 2-3 weeks ago I emailed about a memory leak in my application. I then found some problems in my code (I wasn't closing IndexSearchers explicitly) and took care of those. Now I see my app is still leaking memory - jconsole clearly shows the "Tenured Gen" memory pool getting filled up until I hit the OOM, but I can't seem to pin-point the source.
I found that a bunch or o.a.l.index.* objects are not getting GCed, even though they should. For example: $ jmap -histo:live 7825 | grep apache.lucene.index | head -20 | sort -k2 -nr num #instances #bytes class name -------------------------------------- 4: 1764840 98831040 org.apache.lucene.index.CompoundFileReader$CSIndexInput 5: 2119215 67814880 org.apache.lucene.index.TermInfo 7: 1112459 35598688 org.apache.lucene.index.SegmentReader$Norm 9: 2132311 34116976 org.apache.lucene.index.Term 12: 1117897 26829528 org.apache.lucene.index.FieldInfo 13: 225340 18027200 org.apache.lucene.index.SegmentTermEnum 15: 589727 14153448 org.apache.lucene.index.TermBuffer 21: 86033 8718504 [Lorg.apache.lucene.index.TermInfo; 20: 86033 8718504 [Lorg.apache.lucene.index.Term; 23: 86120 7578560 org.apache.lucene.index.SegmentReader 26: 90501 5068056 org.apache.lucene.store.FSIndexInput 27: 86120 4822720 org.apache.lucene.index.TermInfosReader 33: 86130 3445200 org.apache.lucene.index.SegmentInfo 36: 87355 2795360 org.apache.lucene.store.FSIndexInput$Descriptor 38: 86120 2755840 org.apache.lucene.index.FieldsReader 39: 86050 2753600 org.apache.lucene.index.CompoundFileReader 42: 46903 2251344 org.apache.lucene.index.SegmentInfos 43: 93778 2250672 org.apache.lucene.search.FieldCacheImpl$Entry 45: 93778 1500448 org.apache.lucene.search.FieldCacheImpl$CreationPlaceholder 47: 86510 1384160 org.apache.lucene.index.FieldInfos I'm running my app in search-only mode - no adds or deletes. The counts of these objects just keeps going up, even though I am explicitly closing the IndexSearcher. I can see that file descriptors _are_ freed up after searcher.close(), because lsof no longer shows them, but the above objects just linger and accumulate, even when I force GC via jconsole or via the profiler. I thought maybe various *Readers are not getting close()d, but I've double-checked all *Readers above, and they all seem to close their IndexInput references. The static nested class CompoundFileReader.CSIndexInput has a close() without any implementation. At first I thought that was an omission, but adding a close of the inner IndexInput there resulted in a search-time error. I've added the lovely print debugging to various close() methods and see those methods being called. I've added finalize() with some print debugging to SegmentReader, TermInfosReader, SegmentTermEnum, FieldsReader, and CompoundFileReader. All but CFReader get finalized after a while. My application is running as a webapp and has thousands of separate indices. This means it's very multi-threaded and the servlet container has a pool of threads that handle requests, and each request may be for a different index. I cache IndexSearchers for a while, and purge/close them every N minutes if they have been idle more than M minutes. It occurred to me last night that things like TermInfosReader and SegmentReader are using ThreadLocal, and since threads are used in a thread pool, and thus shared with requests handling searches against different indices, it's not clear to me what happens with object instances that are put in those ThreadLocals in such scenario. Aren't things going to step on each others' toes? TIR has close() and SR has doClose(), so I put <TL inst>.set(null) there. This immediately got rid of those instances of CompoundFileReader.CSIndexInput in my dev environment!!!! Yeeees! But in my dev environment I tested my additions by slamming my app against a *single* index. I took my modified Lucene to production, and quickly saw all those o.a.l.index.* objects accumulate again. I also see a lot of ThreadLocal's kids: 16: 419387 13420384 java.lang.ThreadLocal$ThreadLocalMap$Entry I *think* that points out to some issues with how that ThreadLocal is used there, in a multi-threaded, multi-index environments. I'm running JDK 6, and while this problem sounds a bit like LUCENE-436, I'm not yet sure if it's the same thing. Because my IndexSearchers (and thus all those o.a.l.index.* objects) are long-lived, and threads are shared and reused for searching of other indices, those close() and doClose() methods are not called at the end of the request life-cycle, so at the end of the request those TL instances will *still* have something in them. When their thread is later reused for searching of another index, new data will be put in them, but the old data will never be cleaned out! No? It seems a bit odd, but with this ThreadLocals, shouldn't a multi-threaded, multi-index webapp really have to "clean" those ThreadLocal instances either before or at the end of the request? I'm running out of ideas, and was wondering if anyone has any thoughts about what could still be holding references to the above classes. I have some 20-30MB memory snapshots (via YourKit) and heap dumps (via jmap), if anyone is interested. Thanks, Otis --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
