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Re: [eclipselink-dev] Question about performance issue withSeqencingManager
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Mitesh,
The best solution is to use sequencing connection pool - that's possible in
case you use nonjtaDataSource (which used always to be the case with
GlassFish?).
There's https://bugs.eclipse.org/bugs/show_bug.cgi?id=220402 describing the
issue, the fix and the workaround.
Thanks,
Andrei
----- Original Message -----
From: "Mitesh Meswani" <Mitesh.Meswani@xxxxxxx>
To: <eclipselink-dev@xxxxxxxxxxx>
Sent: Thursday, March 26, 2009 9:09 PM
Subject: [eclipselink-dev] Question about performance issue
withSeqencingManager
Hi,
We seem to have a performance issue with Table Sequences while running
inside container ( => external transaction controller). If multiple
threads try to do getNextValue() on a table sequence and our preallocation
bucket is empty and external transaction controller is used, all of them
can reach the code at line 468 of
SequencingManager.Preallocation_Transaction_NoAccessor_State.getNextValue()
which calls sequence.getGeneratedVector(...) . This would result in all of
them issuing an update statement to the sequence table and being blocked
out by database till preceding threads' transaction commits. The code of
Preallocation_Transaction_NoAccessor_State.getNextValue() is explicitly
written to not obtain locks around sequence.getGeneratedVector(...) if
running with external transaction controller. There is fair amount of
comment written but some how I am still not able to figure out why we are
not obtaining locks for this case. Can some one familiar with history of
the code comment on this.
Thanks,
Mitesh
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