[jira] Commented: (DERBY-3596) Creation of logical connections from a pooled connection causes resource leak on the server

["Kathey Marsden (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-3596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12599175#action_12599175 ] 

Kathey Marsden commented on DERBY-3596:
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I am about even on the two options.  The simple fix seems less risky and less likely to have bugs, but I don't know if the complex fix has other performance benefits.  Just a nit on the fix.  It would be good to mention the bug number in the comments where you talk about the bug, so future readers can refer to this conversation.


> 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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