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From André Warnier>
Subject Re: Application crash after Migrate to different ESX
Date Thu, 19 May 2011 07:29:58 GMT
הילה wrote:
> Hey,
> All of you basically asked about the connection pool I'm using.
> I stated at the beginning that I'm using JDBC connection pool.
> I implement it in the xml file under conf\catalina\localhost, under resource
> tag-
> *factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"*
> with placing tomcat-jdbc.jar  in the catalina_home\lib folder.

Yes, but did you actually ever bother to read its documentation, e.g. at ?
(particularly starting with the attribute "testOnBorrow")

I do not know much about these things, but just entering ""org.apache.tomcat.jdbc.pool" in

Google, and reading that documentation leads me to believe :
- that there are N database connections in the pool
- that they can be checked regularly in the background for validity,
- that a non-valid connection automatically gets dropped from the pool, and replaced by a

new one when needed
- that you can pretty much set any aspect of that mechanism by those attributes
- and that you can log what happens

So, if you are using that pool, I basically do not understand why you would need any 
additional mechanism to overcome the loss of a db connection when your VM is migrated.
Particularly that "smart keep alive" you keep talking about, but never telling us where it

comes from and where it is inserted in that architecture.

> we use the JTDS driver (I tried the Microsoft JDBC, but its performance is
> poor compared to the JTDS driver of sourceforge)
> Someone in my company suggested that the problem can rely in either of these
> JARs.
> so I will check with the tomcat-dbcp.jar as scenario 1, sql-jdbc.jar as
> scenario2, and maybe both combined as scenario 3.
> scenario 4 will be testing the behavior while validation is configured.

Sure, add some extra variables to the problem.  That will make it a lot simpler to find 
out what happens.

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