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https://issues.apache.org/jira/browse/DERBY-3354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12569268#action_12569268
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Øystein Grøvlen commented on DERBY-3354:
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Kathey, I agreed that more needs to be done for a final patch. I just put
together a patch with the core fix to make it possible to try out the fix.
To your issues:
1) Creating a finally block in EmbedBlob seems like a good idea. I also agree
that we can remove similar code from the stored procedures.
2) I will think about solution for jdk15. The problem introduced by 10.3 is
that the lob mapping keeps Blob/Clob objects alive that earlier would be gc'ed
when it was no longer referred by the user. I guess another level of
indirection would make it possible to use finalizers to clean up, but I am not
sure that is a good idea.
A work-around is to not create Blob objects in the first place, but use
ResultSet#getBytes etc instead. So the problem is limited to the case where a
Blob object need to be accessible after a call to ResultSet#next, but not until
commit.
3) Seems like there is come concurrent access to the HashMap. I would guess
that this is because the iterator created by rollback, detects that the
underlying collection has been changed. Probably through the calls to free in
the loop using the iterator. I think this show that something needs to be
reorganized a bit here.
> Select from large lob table with embedded gives OutOfMemoryError
> ----------------------------------------------------------------
>
> Key: DERBY-3354
> URL: https://issues.apache.org/jira/browse/DERBY-3354
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.3.1.4, 10.3.2.1, 10.4.0.0
> Reporter: Kathey Marsden
> Attachments: derby-3354.diff, LocLeak.java
>
>
> Retrieving from a large table with lobs gives an OutOfMemoryException, even
> if free() is explictly called on the lob. I believe this is because
> EmbedConnection.addLobMapping is called for every lob creation but is never
> cleared until commit or rollback, even if the lob is freed.
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