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From Jose MarĂ­a Zaragoza <demablo...@gmail.com>
Subject Re: [jdbc-pool] Validation query leaves transaction open
Date Fri, 12 Aug 2016 05:55:32 GMT
2016-08-11 21:33 GMT+02:00 John Huss <johnthuss@gmail.com>:
> I have verified that in version 8.0.36 of tomcat jdbc the validation query
> functionality does not commit the transaction it starts in order to run the
> validation query, which can cause an open transaction for a very long time
> (possibly until the database crashes).  This seems to be especially
> problematic if you have a large pool where the connections are idle for a
> large period of time.
>
> I also tested against version 9.0.0M9, and in that version the problem is
> fixed.  However, nothing about this appears in the release notes for any
> version (9.0, 8.5, or 8.0).  If this bug has indeed been fixed it should be
> documented in the release notes.  Also, back-porting the fix to the 8.0
> branch would be very helpful.
>
> For the time being I am working around the problem by changing my
> validation query from "SELECT 1" to be "SELECT 1; COMMIT" (using
> postgresql).  This prevents the issue.


I wonder why a validationQuery needs to open a new transaction


>
> This was reported previously (three years ago) here:
> https://mail-archives.apache.org/mod_mbox/tomcat-users/201301.mbox/%3CCAPw873vy%2B9kWMQiFPbnTX6g1FSQ8oTVhDJ3Zagp9UkUZ3d5qjw%40mail.gmail.com%3E
>
> Thanks,
> John

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