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From "Simon Helsen (JIRA)" <>
Subject [jira] [Commented] (JENA-91) extremely large buffer is being created in ObjectFileStorage
Date Thu, 18 Aug 2011 18:22:27 GMT


Simon Helsen commented on JENA-91:


ok, so I applied your patch and executed it without problems (Windows 7 / 64 bit and IBM JRE
6). However, when looking at the test code, I notice you only entertain 1 writerb (and N readers),
is that right? My test scenario executes many readers and writers at the same time. We deliberately
removed our own conservative N-1 read/write locking because our expectation is that a transactional
system will manage the locking internally with as little contention as possible.

Perhaps we are not starting from the same premise


> extremely large buffer is being created in ObjectFileStorage
> ------------------------------------------------------------
>                 Key: JENA-91
>                 URL:
>             Project: Jena
>          Issue Type: Bug
>          Components: TDB
>         Environment: Windows (and I presume any little endian system)
>            Reporter: Simon Helsen
>            Assignee: Andy Seaborne
>            Priority: Critical
>         Attachments: TestTransSystem.patch
> I tried to debug the OME and check why a bytebuffer is causing my native memory to explode
in almost no time. It all seems to happen in this bit of code in com.hp.hpl.jena.tdb.base.objectfile.ObjectFileStorage
(lines 243 onwards)
>   // No - it's in the underlying file storage.
>         lengthBuffer.clear() ;
>         int x =, loc) ;
>         if ( x != 4 )
>             throw new FileException(""+loc+")["+filesize+"]["+file.size()+"]:
Failed to read the length : got "+x+" bytes") ;
>         int len = lengthBuffer.getInt(0) ;
>         ByteBuffer bb = ByteBuffer.allocate(len) ;
> My debugger shows that x==4. It also shows the lengthBuffer has the following content:
[111, 110, 61, 95]. This amounts to the value of len=1869495647, which is rather a lot :-)
Obviously, the next statement (ByteBuffer.allocate) causes the OME.

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