connection pool is not being kept alive by dbcp
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Key: DBCP-266
URL: https://issues.apache.org/jira/browse/DBCP-266
Project: Commons Dbcp
Issue Type: Bug
Environment: Apache Tomcat 6.0.16
Jdk 1.6.0_05-b13 Sun Microsystems Inc.
Linux 2.6.18-53.1.4.el5 amd64
mysql-connector-java-5.0.8-bin.jar
Reporter: Marco Boniardi
In our production environment, randomly the connection pool in Tomcat 6.0.16
collapses, no errors, just hunged.
You can not retrive it from context with a lookup, we can not have connections.
All requests hunged. We think it's closely related to db idle connection
management, with idle connection closed server side due to timeout while the
connection pool does not realize this.
After a couple of week of investigation, we discovered this:
we see validation query running, but very often the time between 2 validation
query runs is not timeBetweenEvictionRunsMillis.
It's double, we wrote 40 seconds, it runs every 80 seconds.
For some reason, in some machine of our cluster (older tomcat restart?) we see
validation query running every 160 seconds for all connection, 4 times
timeBetweenEvictionRunsMillis, and it's stable, always 160 sec., even if we
don't know if tomorrow it goes to 320sec. or it stays to 160. In our idea there
is something wrong with the Timer that manage to run query validation for idle
connection. Problably timeBetweenEvictionRunsMillis grows over server timeout
period causing connections pool collape.
Till 3 weeks ago we had Tom 5.0.x and everything was perfect.
After we moved to Tomcat 6.0.16 we have to restart 1-2 servers /day in a 10
serves cluster due to hunged connection pool.
The problem is not related to traffic because it happends night time too.
I hope this can help to figure out the problem.
Regards
Marco Boniardi
<Resource
name="jdbc/bestprices"
type="javax.sql.DataSource"
initialSize="5"
maxActive="15"
maxIdle="15"
minIdle="5"
maxWait="5000"
testOnBorrow="false"
testWhileIdle="true"
timeBetweenEvictionRunsMillis="40000"
minEvictableIdleTimeMillis="240000"
validationQuery="SELECT 1"
username="bestprices_user"
password="xxxxxxxx"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://vgdb05:3306/bestprices?zeroDateTime-Behavior=convertToNull"
/>
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