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From Daniel Mikusa <dmik...@gopivotal.com>
Subject Re: Reg: Connection pool stats
Date Mon, 11 Nov 2013 12:52:22 GMT
On Nov 11, 2013, at 12:59 AM, Anu Prab <anuprab2@gmail.com> wrote:

> On Nov 7, 2013, at 11:58 PM, Anu Prab <anuprab2@gmail.com> wrote:
> 
>>>> I am using Tomcat 7.0.42 and Tomcat jdbc pool.
>> 
>>> Just to be perfectly clear, how are you using this?  With a <Resource/>
>> tag in your Tomcat >configuration or are you creating the pool in your
>> code?  Either way, include the necessary >config or code which shows how
>> you've defined the pool.
>> 
>>> The pool configuration is in context.xml. A sample of the config looks
> like
>> this:
>> 
>>> <Resource name="jdbc/name"
>>>             auth="Container"
>>>            type="javax.sql.DataSource"
>>>             fairQueue="true"
>>>            factory="<customized-factory>"
> 
>> What factory are you using?  It's important to share.  Without it we don't
> know which pool you're using.
> 
> A customized factory which extends org.apache.tomcat.jdbc.pool.
> DataSourceFactory
> Few minutes, not sure of the exact timing. Yes, all are 0.
> 
>> Also, what happens when you try to get a connection after the pool count
> has dropped to 0?  >Does it get a new connection?  Does it hang waiting?
> Does it generate any error messages?
> 
>> Is there any reason why you might be getting disconnected from the
> database side or from a >firewall in between your application and the
> database?
> 
> I can still get newer connections even after the count drops to 0.
> 
> 
> Hi,
> 
> Also, when I enabled logAbandoned as you suggested, I see this exception
> after about 17-18 minutes.
> 
> org.apache.tomcat.jdbc.pool.ConnectionPool abandon
> WARNING: Connection has been abandoned
> PooledConnection[oracle.jdbc.driver.T4CConnection@2726965a
> ]:java.lang.Exception
>        at
> org.apache.tomcat.jdbc.pool.ConnectionPool.getThreadDump(ConnectionPool.java:1065)
>        at
> org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:707)
>        at
> org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:634)
>        at
> org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:188)

This explains the behavior that you're seeing.  It appears that your connections are being
flagged as abandoned and thus removed from the pool.  

Take a look at the generated stack trace and see what part of your code is holding onto the
connection.  This could be legitimate, in the case where you have a long running process (like
a batch job) or it could be a code error (like you don't have proper try..catch..finally blocks
setup to close connections).

Dan

> 
> -Anu


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