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https://issues.apache.org/jira/browse/DERBY-3596?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kristian Waagan updated DERBY-3596:
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Attachment: complex-fix-heap.png
simple-fix-heap.png
nofix-heap.png
Attaching three images showing the heap usage of the various builds: no fix,
simple fix and complex fix.
Note the left side axis, it is not the same across all the images!
I used the attached repro to measure performance, and JConsole to monitor heap
usage. I ran the repro 10 times, each run lasting 30 seconds using Sun JDK
1.6.0 with default settings on my dual core machine with 4 GB memory.
Number of iterations done by the repro;
- no fix: 48 000 [25 - 56]
- simple fix: 78 000 [70 - 79]
- complex fix: 125 000 [120 - 128]
Note that the complex fix is not optimal, but feasible without changing
the client driver as well. I haven't verified, but I believe it should
work fine with older client versions. The simple fix keeps the semantics
unchanged.
> Creation of logical connections from a pooled connection causes resource leak
> on the server
> -------------------------------------------------------------------------------------------
>
> Key: DERBY-3596
> URL: https://issues.apache.org/jira/browse/DERBY-3596
> Project: Derby
> Issue Type: Bug
> Components: Network Client, Network Server, Performance
> Affects Versions: 10.1.3.1, 10.2.2.0, 10.3.2.1, 10.4.1.3, 10.5.0.0
> Reporter: Kristian Waagan
> Assignee: Kristian Waagan
> Attachments: complex-fix-heap.png, ConnectionPoolingBug.java,
> derby-3596-1a-complex_approach.diff, derby-3596-2a-simple_approach.diff,
> nofix-heap.png, simple-fix-heap.png
>
>
> When using ClientConnectionPoolDataSource and connection pooling, a new
> connection / transaction is created for every new logical connection, and the
> resources are not freed / cleaned up in the server. They are not even cleaned
> up when the physical connection (ClientPooledConnection) is closed.
> A logical connection is obtained by invoking
> ClientPooledConnection.getConnection().
> I have observed that if you run the repro enough times against the same
> server, the number of transaction in the transaction table will be reduced
> now and then. I believe this is garbage collection, but I have not
> investigated the problem enough to tell for sure what's going on.
> I have also seen some locks not being freed, causing timeouts in some
> applications. I don't have a repro for the lock problem at this time, but it
> is very likely related to this issue.
> Note that XA connections are handled differently on the server, and do
> probably not have this problem.
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