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From "Kathey Marsden (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-4050) Multithreaded clob update causes growth in table that does not get reclaimed
Date Fri, 06 Feb 2009 23:54:59 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4050?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kathey Marsden updated DERBY-4050:
----------------------------------

    Attachment: derby-4050_diff.txt

Attached is a patch for this issue.  Per Mike's suggestion I changed the code to call getPage()
 instead of getPageNoWait.  I kept the null check but got rid of the retries.  I am not totally
sure that the null check is still needed though.

I included  Mike's debug statements for the other cases where space may not be reclaimed after
three tries.  After this issue is resolved I will log another Jira issue to address those
cases.  I don't want to try to address them in this patch because I don't have reproducible
cases for them.

Also included is a regression test.

I am running tests now.



> Multithreaded clob update causes growth in table that does not get reclaimed
> ----------------------------------------------------------------------------
>
>                 Key: DERBY-4050
>                 URL: https://issues.apache.org/jira/browse/DERBY-4050
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>    Affects Versions: 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.0.0
>            Reporter: Kathey Marsden
>         Attachments: ClobGrowth.java, derby-4050_diff.txt, derby-4050_more_debug.diff,
derby.log.growth, derby.log.nogrowth
>
>
> Doing a multithreaded update of a Clob table causes table growth that does not get reclaimed
except by compressing the table.  The reproduction has a table with two threads. One  thread
 updates row 1 repeatedly with 33,000 character clob. The other thread updates row 2 with
a small clob, "hello".  The problem occurs back to 10.2 but seems much worse on trunk than
10.2.   The trunk database grew to 273MB on trunk after 10000 updates of each row. The 10.2
database grew only to 25MB.  If the update is synchronized there is no growth.
> I will attach the repro.

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