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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 09:17:59 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13005564#comment-13005564
] 

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

To illustrate the point in my previous comment, here's the first deadlock error when running
the attached repro:

A lock could not be obtained due to a deadlock, cycle of locks and waiters is:
Lock : ROW, T, (1,7)
  Waiting XID : {182, S} , APP, select x from t where x = 1
  Granted XID : {162, X} 
Lock : ROW, T, (1,8)
  Waiting XID : {162, S} , APP, select x from t where x = 2
  Granted XID : {166, X} 
Lock : ROW, T, (1,9)
  Waiting XID : {166, S} , APP, select x from t where x = 3
  Granted XID : {170, X} 
Lock : ROW, T, (1,7)
  Waiting XID : {170, S} , APP, select x from t where x = 1
. The selected victim is XID : 182.

No one is waiting for tx 182, so aborting it doesn't really resolve the deadlock, and therefore
other transactions will have to be aborted later. Also note that the data for row (1,7) has
been split in two in the output.

> 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
>
>
> 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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