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https://issues.apache.org/jira/browse/JENA-91?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13089046#comment-13089046
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Simon Helsen commented on JENA-91:
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Paolo, I am trying to debug/dig into the code to see if I can make sense of why
this concurrency is failing. There is one thing I don't quite understand. In
the begin$ method in the transaction manager on line 319/320, I notice that if
the transaction is READ, the components are always empty, so, a READ
transaction never really begins. A WRITE transaction seems to start the begin
fine. Is this how it is supposed to be? I was trying to understand why the
components may be empty, but I didn't see through the long change of embedded
objects. Just thoughts, perhaps it helps you
I do think however, that with the patched TestTransSystem (which only has 1
read and 1 write thread), it should be easier to debug the problem.
> extremely large buffer is being created in ObjectFileStorage
> ------------------------------------------------------------
>
> Key: JENA-91
> URL: https://issues.apache.org/jira/browse/JENA-91
> Project: Jena
> Issue Type: Bug
> Components: TDB
> Reporter: Simon Helsen
> Assignee: Andy Seaborne
> Priority: Critical
> Attachments: TestTransSystem.patch, TestTransSystem2.patch,
> TestTransSystem3.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 = file.read(lengthBuffer, loc) ;
> if ( x != 4 )
> throw new
> FileException("ObjectFile.read("+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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