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From Joe Baldwin <jfbald...@earthlink.net>
Subject Re: Cayenne Supported DBCP Properties
Date Thu, 27 May 2010 16:16:58 GMT
Andrus,

Thanks again for your suggestion.  It *appears* to have revealed another possibly associated
problem.

I have been working on a "load time" problem that has the symptoms of causing a jsp page using
Cayenne (connecting to MySQL 5.0.x) taking about 30-60 secs to load. With the help of the
Cayenne team it appears that it was not due to Cayenne.  However, the webhost tech person
believes that it cannot be MySQL 5.0.x.

Well almost immediately after getting the "testWhileIdle" configuration working I got another
load-event with the corresponding Catalina log exception:

	java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction

I did some more research and the web-comments (while not conclusive) appear to point to the
InnoDB table locking issue that I found documented in some MySQL 5.0.x bug reports.

Question:
Since I cannot reproduce this error on my development machine (and my head is about to explode
on this one :) ), do you think that there a chance that this is in the DBCP Pool Manager (that
I have just configured for Cayenne), or is it more likely that it is MySQL 5.0.x InnoDB?

(My only test left is to request that they move the project to a new server with MySQL 5.1.x)

Thanks for all your help so far,
Joe








On May 27, 2010, at 10:23 AM, Andrus Adamchik wrote:

> 
> On May 27, 2010, at 5:04 PM, Joe Baldwin wrote:
> 
>> thanks for the "testWhileIdle" suggestion.  This appears to cooperate with validationQuery
and allow a startup.  (I am also hopeful that it addresses a long standing problem with MySQL
connections.)
> 
> So if it works, don't fix it :-)
> 
>> However, it appears that there is a repeatable problem with testOnBorrow & validationQuery
(i.e. Tomcat throws an exception on startup and the app fails to start).  Is it possible that
there is a bug with these two parameters?
> 
> The link that I googled and mentioned in my previous email suggests that there is - in
commons-pool or commons-dbcp. You may try to follow up with the Apache Commons folks if you
want to dig deeper.
> 
> Andrus


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