Hi,
I'm having some trouble with my dbcp pool freezing up when running a load,
and am having trouble figuring out why. I have enabled JMX on the server
and connected via jConsole, and see that all my threads are in the WAITING
state from
org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:810)
I don't believe I have any connection leaks in my code (I explicity close
all my connections in a try/catch/finally), and yet, once all my connections
are used up, all processes hang. I have tried enabling removeAbandoned
connections, but it doesn't seem to do anything either. If I look at the
numActive threads in jConsole, it is always stuck at maxThreads (in my case,
8). Increasing the number of maxThreads will unblock the problem, but it
doesn't resolve the underlying question as to why this happens in the first
place. I would expect that if some threads are "busy" doing nothing, that
they would be cleaned up by the removeAbandoned option, and released to the
next available thread.
<Resource name="jdbc/db" auth="Container"
type="javax.sql.DataSource" username="db" password="db"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/db?autoReconnect=true"
maxActive="8" maxIdle="4"
removeAbandoned="true"
removeAbandonedTimeout="20"
logAbandoned="true"
/>
Example jConsole thread trace:
Name: http-8112-12
State: WAITING on org.apache.tomcat.dbcp.dbcp.abandonedobjectp...@1cee361
Total blocked: 634 Total waited: 285
Stack trace:
java.lang.Object.wait(Native Method)
java.lang.Object.wait(Object.java:474)
org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:810)
org.apache.tomcat.dbcp.dbcp.AbandonedObjectPool.borrowObject(AbandonedObjectPool.java:84)
org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:96)
org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)
...
All the threads just wait in this state perpetually.
I was hoping to go through the source code for the pooling, but I can't seem
to find the srcs for tomcat-dbcp.jar anywhere. I realize that they are a
subset of the commons-dbcp library, but was wondering if the actual sources
that make up tomcat-dbcp exist anywhere. I can't find them anywhere on the
tomcat site.
Any ideas, suggestions or pointers would be greatly appreciated.
Thanks!
Eric
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