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From Phil Steitz <>
Subject Re: [dbcp] Re: DBCP minIdle
Date Sun, 20 Jun 2010 01:28:00 GMT
mehul mehta wrote:
> Here is our config:
>   maxActive="10000" maxWait="60000" minIdle="25" maxIdle="50" 
>         validationQuery="select current_date from sysibm/sysdummy1" 
>         testOnBorrow="true" 
>         testWhileIdle="false" 
>         testOnReturn="true" 
>         timeBetweenEvictionRunsMillis="5000" 
>         minEvictableIdleTimeMillis="60000" 
>         numTestsPerEvictionRun="5" 
>         removeAbandoned="true" 
>         removeAbandonedTimeout="300" 
>         logAbandoned="true"
> It appears that our minEvictableIdleTimeMillis is too short. Probably, we should set
it to the default which is 30 minutes.
> Also, is there any down side of setting timeBetweenEvictionRunsMillis to -1 (no evictor)?
> Not sure if you observe any thing else in the config that can cause performance issues?

Yes, running the evictor every 5 seconds is likely to cause
performance problems, especially during periods of heavy load or
when using pool 1.3.

If you turn off the evictor altogether, minIdle will not be
maintained, there will be no abandoned connection removal, and no
"eviction" of connections that have been idle in the pool for longer
than the minEvictableIdleTimeMillis.  If your application does not
need these things, you are better off turning off the evictor.

Having maxActive so much larger than maxIdle could cause connection
churn if load comes in spikes and you regularly go significantly
above 50 active connections.

> - Mehul
>> Date: Sat, 19 Jun 2010 12:45:31 -0400
>> From:
>> To:
>> Subject: [dbcp] Re: DBCP minIdle
>> mehul mehta wrote:
>>> Hello, We have dbcp configuration in production set as minIdle = 25, maxIdle
= 50, maxActive = 10000. We often experience slow down in queries to the database that normally
do not take that long. We are pretty sure that it is not the database.Let us say the idle
connections are 25. Now one of the idle connections is used up. Does dbcp create a new connection
right away to maintain 25 idle connections. Or does dbcp wait for 25 idle connections to be
used up and then create 25 new connections at one time? Regards,
>> The pool does not attempt to ensure minIdle after each
>> borrow/return. It does this each time the "evictor" maintenance
>> thread runs, which is once every timeBetweenEvictionRunsMillis
>> milliseconds.
>> maxIdle is enforced on each return to the pool - i.e., if there are
>> maxIdle connections idle in the pool when a connection is returned,
>> it is destroyed.
>> What versions of dbcp and pool are you running and what is your
>> timeBetweenEvictionRunsMillis setting?
>> Phil
>>> - Mehul 		 	   		  
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