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From Tomás Tormo <tto...@indenova.com>
Subject Re: Tomcat and database connection
Date Thu, 13 May 2010 10:13:30 GMT
>
> http://commons.apache.org/dbcp/configuration.html
>    
Thanks, I was already checking that.

> I don't know anything about Introscope.
It just an monitoring tool application

> If maxActive is larger than the number of active connections, then
> there's nothing wrong there, is there?  I'm not sure what you're trying
> to explain by that.
>
>    
Yes maxActive is larger than the active connections. Both queries (the 
one running and the one stalled) are trying to access the same register 
in BBDD (is the case when two different users are doing the same), but 
the query is just a simple SELECt, that's why I think is surprising that 
the second one is getting stalled...

> If you can see some stalled connections, take a thread dump to see what
> they're doing/waiting on.

Could I use jvisualvm for that? I knew I could see threads state there, 
but I didn't know I could see why they are waiting...
Sorry for my ignorance, I'm just starting in this field... :S



On 13/05/10 11:05, Pid wrote:
> On 13/05/2010 09:35, Tomás Tormo wrote:
>    
>> Greetings
>>
>> I would like to understand correctly how Tomcat database pool works.
>>      
> It's a repackaged version of Apache Commons DBCP.
>
>    
>> As I understand, when the application starts, a pool connection is
>> created with *initialSize* connections (0 by default).
>>
>> Later on, new connections are created on demand of the application,
>> untill it reaches the *maxActive* connections. If *maxActive* has been
>> reached and the application requests for a new connection, the pool will
>> wait *maxWait* milliseconds for a free connection.
>>
>> If any connection has been released, it will be kept as idle as long as
>> *maxIdle* is not reached. No more connections will be created if there
>> are *minIdle* or more connections in the pool in idle state.
>>      
> http://commons.apache.org/dbcp/configuration.html
>
>    
>> ¿Am I right?
>>
>> But I still have some questions:
>>
>> ¿How to see the pool connection state in real time? (idle connections,
>> active connections, etc). We are using Introscope for monitoring an
>> application, and we can see some stalled connections... but the
>> maxActive parameter is far bigger (100) than the actived connections
>> shown by Introscope (24). This is happening with Tomcat 5.5 on CentOs
>> using Java 1.6.
>>      
> I don't know anything about Introscope.
>
> If maxActive is larger than the number of active connections, then
> there's nothing wrong there, is there?  I'm not sure what you're trying
> to explain by that.
>
> If you can see some stalled connections, take a thread dump to see what
> they're doing/waiting on.
>
>
> p
>
>
>    


-- 
Un saludo,

Tomás Tormo Franco
Area de sistemas

INDENOVA S.L.
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Tel. (34) 96 381 99 47
Fax. (34) 96 381 99 48

ttormo@indenova.com
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