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https://issues.apache.org/jira/browse/DERBY-3571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12582698#action_12582698
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Kristian Waagan commented on DERBY-3571:
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Thanks for the comments Knut Anders.
This is work in progress, so the next patch will have some changes.
I will fix the typos, and also add more comments/JavaDoc. I renamed the method
keepLocatorColumnAlive to markLOBAsAccessed, in hope that it gives more
meaning...
See below regarding the rest of your comments.
* NoOpLOBStateTracker
Yes, that is a good idea. It is now a singleton.
It is also correct that it will be used for result sets without LOBs.
* Fixed assert.
* Rewrote code block for compactness.
On a side note, this code will only be in 10.3. For 10.4 and trunk I plan to
make a few changes so it is no longer required to know if it is a Blob or a
Clob. This requires two changes; a small refactoring (issue not yet created)
and optimization 1 mentioned in my earlier comment.
I will upload a replacement patch shortly, which addresses other problems in 1a.
> LOB locators are not released if the LOB columns are not accessed by the
> client
> -------------------------------------------------------------------------------
>
> Key: DERBY-3571
> URL: https://issues.apache.org/jira/browse/DERBY-3571
> Project: Derby
> Issue Type: Bug
> Components: JDBC, Network Client
> Affects Versions: 10.3.2.1, 10.4.1.0, 10.5.0.0
> Reporter: Kristian Waagan
> Assignee: Kristian Waagan
> Attachments: derby-3571-1a-client_track_lob_fix.diff,
> derby-3571-1a-client_track_lob_fix.stat
>
>
> If the client creates a result set containing LOB locator columns and
> iterates through it without actually accessing the LOB columns, the locators
> are not released.
> The amount of locators and their associated LOB objects causes the server to
> consume large amounts of memory and it eventually gets an OOME.
> There are a few workarounds for this bug:
> a) Access and/or properly close the LOBs (i.e. Blob.free).
> This is partly dependent on DERBY-2892.
> b) Invoke Connection.commit (or rollback) periodically, which causes all
> locators on the connection to be released.
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