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https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13001385#comment-13001385
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Karl Wright commented on DERBY-5073:
------------------------------------
The locks table at the time of a hang looks like this:
ij> select * from syscs_diag.lock_table;
XID |TYPE |MODE|TABLENAME
303942 |ROW |X |JOBQUEUE
303956 |ROW |S |JOBQUEUE
303959 |ROW |S |JOBQUEUE
303962 |ROW |S |JOBQUEUE
304018 |ROW |X |JOBQUEUE
303974 |ROW |X |JOBQUEUE
303987 |TABLE|IX |JOBS
303962 |ROW |X |JOBQUEUE
303965 |ROW |S |JOBQUEUE
303968 |ROW |S |JOBQUEUE
303971 |ROW |S |JOBQUEUE
303974 |ROW |S |JOBQUEUE
303977 |ROW |S |JOBQUEUE
303987 |ROW |S |JOBQUEUE
304018 |ROW |S |JOBQUEUE
303942 |TABLE|IS |CARRYDOWN
303956 |TABLE|IS |CARRYDOWN
303959 |TABLE|IS |CARRYDOWN
303962 |TABLE|IS |CARRYDOWN
303965 |TABLE|IS |CARRYDOWN
303968 |TABLE|IS |CARRYDOWN
303971 |TABLE|IS |CARRYDOWN
303974 |TABLE|IS |CARRYDOWN
303977 |TABLE|IS |CARRYDOWN
304018 |TABLE|IS |CARRYDOWN
303942 |TABLE|IX |PREREQEVENTS
303956 |TABLE|IX |PREREQEVENTS
303959 |TABLE|IX |PREREQEVENTS
303962 |TABLE|IX |PREREQEVENTS
303965 |TABLE|IX |PREREQEVENTS
303968 |TABLE|IX |PREREQEVENTS
303971 |TABLE|IX |PREREQEVENTS
303974 |TABLE|IX |PREREQEVENTS
303977 |TABLE|IX |PREREQEVENTS
304018 |TABLE|IX |PREREQEVENTS
303956 |ROW |X |JOBQUEUE
303977 |ROW |X |JOBQUEUE
303968 |ROW |X |JOBQUEUE
303965 |ROW |X |JOBQUEUE
303959 |ROW |X |JOBQUEUE
303971 |ROW |X |JOBQUEUE
303942 |ROW |S |JOBQUEUE
303942 |TABLE|IX |JOBQUEUE
303942 |TABLE|IS |JOBQUEUE
303956 |TABLE|IX |JOBQUEUE
303956 |TABLE|IS |JOBQUEUE
303959 |TABLE|IX |JOBQUEUE
303959 |TABLE|IS |JOBQUEUE
303962 |TABLE|IX |JOBQUEUE
303962 |TABLE|IS |JOBQUEUE
303965 |TABLE|IX |JOBQUEUE
303965 |TABLE|IS |JOBQUEUE
303968 |TABLE|IX |JOBQUEUE
303968 |TABLE|IS |JOBQUEUE
303971 |TABLE|IX |JOBQUEUE
303971 |TABLE|IS |JOBQUEUE
303974 |TABLE|IX |JOBQUEUE
303974 |TABLE|IS |JOBQUEUE
303977 |TABLE|IX |JOBQUEUE
303977 |TABLE|IS |JOBQUEUE
303987 |TABLE|IS |JOBQUEUE
304018 |TABLE|IX |JOBQUEUE
304018 |TABLE|IS |JOBQUEUE
63 rows selected
Since the process is still active, other threads that the ones that get hung
may well be active. I have confirmed that all blocked threads are blocked due
to database, and for no other reason.
> 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
>
> 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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