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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-5073) Derby deadlocks without recourse on simultaneous correlated subqueries
Date Fri, 11 Mar 2011 18:19:59 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13005764#comment-13005764
] 

Knut Anders Hatlen commented on DERBY-5073:
-------------------------------------------

Thanks for the feedback, Bryan and Kathey. I'll polish the patch and incorporate the repros
attached to this issue and DERBY-3980 into a JUnit test that can run as part of the regression
test suite.

Since we don't know for sure that the repro I attached reproduces the exact same problem as
originally reported, we should probably check in the fix under DERBY-3980 and mark that issue
as resolved. When Karl gets a chance to verify that this also fixes the problem he saw, we
can close this issue as a duplicate of DERBY-3980.

And, yes, I'll annotate the deadlock detection code with comments reflecting my understanding
of what it does and how it should work. Good idea. Thanks!

> Derby deadlocks without recourse on simultaneous correlated subqueries
> ----------------------------------------------------------------------
>
>                 Key: DERBY-5073
>                 URL: https://issues.apache.org/jira/browse/DERBY-5073
>             Project: Derby
>          Issue Type: Bug
>          Components: Services
>    Affects Versions: 10.0.2.1, 10.1.2.1, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.3.0, 10.6.2.1,
10.7.1.1, 10.8.0.0
>            Reporter: Karl Wright
>         Attachments: Derby5073.java, derby-5073-1a.diff, derby-5073-1b.diff
>
>
> When the following two queries are run against tables that contain the necessary fields,
using multiple threads, Derby deadlocks and none of the queries ever returns.  Derby apparently
detects no deadlock condition, either.
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE t1.parentidhash
IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid) AND t0.jobid=?
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE t1.parentidhash
IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid AND t1.newField=?) AND t0.jobid=?
> This code comes from Apache ManifoldCF, and has occurred when there are five or more
threads trying to execute these two queries at the same time.  Originally we found this on
10.5.3.0.  It was hoped that 10.7.1.1 would fix the problem, but it hasn't.

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