Filip,
Thanks for the reply. I have my doubts about unclosed connections
as the cause because this application ran for a year using an Oracle
DataSource class with no problems. We moved to DPCP in order to support
non-oracle DBs and that is when the problem started.
If the problem was simply running out of connections would there be
all these threads in wait state? getConnecton() throws an SQLException
if it can't get a connection. Wouldn't that case apply if there were no
connections available? Based on the thread dump the problem seems to be
related to a locked object that the getConnection logic is trying to access.
Any help or advice will be greatly appreciated,
-=beeky
Filip Hanik - Dev Lists wrote:
looks like you are running out of connections, and on the contrary to
what you say, you are not closing them correctly :)
what if you replace the static connection object with a new one before
you called close on the old one
Filip
Wm.A.Stafford wrote:
Our Tomcat instance has been hanging add odd intervals. We see many,
many identical thread dumps like this:
http-8082-Processor84" daemon prio=10 tid=0x0887c000 nid=0x5663 in
Object.wait() [0x6c1ad000..0x6c1ae030]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x75132118> (a
org.apache.commons.dbcp.AbandonedObjectPool)
at java.lang.Object.wait(Object.java:485)
at
org.apache.commons.pool.impl.GenericObjectPool.borrowObject(Unknown
Source)
- locked <0x75132118> (a org.apache.commons.dbcp.AbandonedObjectPool)
at
org.apache.commons.dbcp.AbandonedObjectPool.borrowObject(AbandonedObjectPool.java:117)
- locked <0x75132118> (a org.apache.commons.dbcp.AbandonedObjectPool)
at
org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:110)
at
org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:312)
at
dbAccess.FailSafeConnectionPool.getConnection(FailSafeConnectionPool.java:162)
at servlets.ControllerServlet.doGet(ObisControllerServlet.java:93)
There is clearly something pathological going on but I'm not sure
what. It looks to me like this and all the other threads are waiting
on org.apache.commons.dbcp.AbandonedObjectPool which is locked by
another thread. But I can not deduce much more.
We are using dbcp-1.0. The code handles connections rather strangely
but it seems to be closing them correctly. There is one static
Connection object and a call to a local getConnection() calls close()
on this static connection then replaces it with a connection returned
by a call to BasicDataSource.getConnection().
There is one exception handler that calls close() on the
BasicDataSource and then creates a new one. I thought this might be
the problem, that somehow the connections associated with the
previous BasicDataSource were still being held but I can't see a
scenario that would do this.
We are also using a BasicDataSource in our Spring enabled DAOs but
there is no common code sheared by these and the legacy code that is
being fingered by the thread dump.
Any help or advice will be greatly appreciated,
-=beeky
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