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https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13005042#comment-13005042
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Knut Anders Hatlen commented on DERBY-5073:
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I took a look at this in the debugger. The deadlock is indeed detected, and a
victim is chosen and woken up. The victim rechecks that there still is a
deadlock, so that it doesn't have to give up if it's no longer part of a
deadlock. When rechecking, it finds that there is a deadlock, and picks another
victim, whereas it goes back to sleep waiting for the lock again itself. The
new victim will do the same, and pick yet another victim. And so it goes on.
There is code in place to prevent a victim from picking another victim when
rechecking the deadlock, but for some reason that code doesn't work in this
scenario.
> 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
>
>
> 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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