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From הילה <hilavalen...@gmail.com>
Subject Re: Application crash after Migrate to different ESX
Date Thu, 19 May 2011 06:16:22 GMT
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.

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.

Thanks
Hila


2011/5/18 Christopher Schultz <chris@christopherschultz.net>

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> הילה,
>
> On 5/18/2011 4:20 AM, הילה wrote:
> > this behavior occur even when I'm disconnecting the Network card from the
> VM
> > settings and connecting it again.
>
> At least it's reproducible in a way that you're willing to try in
> production. What about reproducing it in development/test environments?
> That would certainly be safer...
>
> > afterwards, the keep alive is alternately unavailable.
>
> That doesn't sound like keep-alive to me.
>
> The JDBC protocol, to my knowledge, does not include any kind of
> keep-alive or similar feature. To get that, you'll have to use some
> other product in order to ensure that connections are valid before
> trying to use them, otherwise you'll get exceptions being thrown.
>
> In the case you posted to start this thread, it looked like the
> connection was closed when it was obtained from a connection pool. How
> does com.vsgaming.app.appContext.getDatabaseConnection  get it's
> database connections? Are you using a connection pool? If so, which one?
>
> It sounds like you haven't enabled connection validation which is really
> the only way to ensure that connections are valid when you check them
> out of a pool. It's too bad that seems to cause crashes in your
> webapp... I've never heard of that before. Sure, it causes a bit of a
> performance drop but you can tune the validation so it doesn't run on
> every connection check-out to help mitigate that performance loss.
>
> I would look into why connection validation causes your webapp to crash.
> (Strictly speaking, nobody in the Java world refers to an exception
> being thrown as a "crash"... it's a relatively frequent occurrence even
> though the user might not like it. Crashing is *much* worse than a
> single request failing due to some exception.)
>
> > looks like it's not
> > always trying to approach the DB opened wireshark and saw that
> ip.addr==DB
> > IP ADDRESS is not always showing results when the keep alive is
> unavailble =
> > he's not trying to get to the DB at all, I think.
>
> I cannot understand what you are saying above. Can you re-phrase it?
>
> > it all sorts out after I restart the tomcat service. this is why I think
> it
> > does related to tomcat.
>
> Re-establishing all the database connections by any means will likely
> correct everything. It still might have nothing to do with Tomcat. If
> you tell us how you do database connection management, it might help.
>
> - -chris
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