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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-5073) Derby deadlocks without recourse on simultaneous correlated subqueries
Date Wed, 09 Mar 2011 17:17:03 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-5073:
--------------------------------------

    Attachment: Derby5073.java

I think I'm able to reproduce the problem. At least, I've been able to construct a deadlock
that looks similar to the one in the lock dump Karl provided. See the attached Java program
(Derby5073.java). There's a cycle involving three transactions, as well as some other transactions
that wait on the same locks without actually being part of the cycle themselves.

When disabling waitTimeout, the program runs forever, whereas it should have been terminated
with a deadlock error. Even when it's stuck, it keeps one CPU fully occupied. Perhaps an infinite
loop in the deadlock detection?

> 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
>            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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