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From "Andy Seaborne (Commented) (JIRA)" <>
Subject [jira] [Commented] (JENA-91) extremely large buffer is being created in ObjectFileStorage
Date Tue, 04 Oct 2011 10:38:34 GMT


Andy Seaborne commented on JENA-91:

The "write: Block in the read cache" is spurious, at least in the TestTransRestart test. 
It happens when committing a transaction, doing a forced write through to the database.  But
blocks can be in the read cache of the underlying database because a write transactions reads
them into it's own transaction view of the data.  .overwrite should just not worry about blocks
in underlying read cache.
> extremely large buffer is being created in ObjectFileStorage
> ------------------------------------------------------------
>                 Key: JENA-91
>                 URL:
>             Project: Jena
>          Issue Type: Bug
>          Components: TDB
>            Reporter: Simon Helsen
>            Assignee: Andy Seaborne
>            Priority: Critical
>         Attachments: JENA-91_NodeTableTrans_r1159121.patch, TestTransSystem.patch, TestTransSystem2.patch,
TestTransSystem3.patch, TestTransSystem4.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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