Re: [c3p0-users] c3p0 connection leak problem

[Steve W. <swa...@mc...>]

hi,

so a Connection "leak" usually means Connections get opened but never closed. here, the immediate error, Connections are failing to open. do you have reason to think that the 1023 open file descriptors represent Connections that were opened but never closed? you might try analyzing the output of lsof (or your operating system's equivalent) to see what these files are. it's possible something else on the machine is bringing open files to their limit, and c3p0 is only experiencing a failure caused by that. (if this is happening, you might not even be able to do a DNS lookup, so the UnknownHostException is not surprising.) alternatively, if you do have hundreds of database Connections somehow opened and never closed, that would be worth looking into.

good luck!

    steve




On Feb 22, 2013, at 2:42 AM, yavuz gokirmak wrote:

> Hi,
> 
> 
> I have an application that have several threads and using c3p0 for lots of database queries. 
> Application works well in several environments but I have problem in one of installations. 
> 
> The reason why I give this information is that we know that there is no connection leak in the code,
> but somehow we face with connection problems in one installation. 
> 
> Below is the error I get. This error is caught repeatedly after some case and as I saw we have lots of open files ( 1023 open file descriptors while the limit is 1024 ) in the system. Open file problem may trigger the below error or the reverse is the case. 
> 
> It is strange that I get "Caused by: java.net.UnknownHostException: name_of_host" unknowhost exceptions.  
> This may be the reason for connection problem but the question is,
> Is this a reason for connection leak? What is your idea?
> 
> 
> ------------------
> 
> 21/Feb/2013 15:11:57   WARN   137479890 [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0] com.mchange.v2.resourcepool.BasicResourcePool(L:1841) - com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@2387802 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (5). Last acquisition attempt exception: 
> java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection
> 	at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:458)
> 	at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:546)
> 	at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:236)
> 	at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
> 	at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
> 	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
> 	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
> 	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:148)
> 	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
> 	at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
> 	at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
> 	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
> Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
> 	at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:392)
> 	at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:434)
> 	at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:687)
> 	at oracle.net.ns.NSProtocol.connect(NSProtocol.java:247)
> 	at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1102)
> 	at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:320)
> 	... 11 more
> Caused by: java.net.UnknownHostException: name_of_host
> 	at java.net.InetAddress.getAllByName0(InetAddress.java:1201)
> 	at java.net.InetAddress.getAllByName(InetAddress.java:1128)
> 	at java.net.InetAddress.getAllByName(InetAddress.java:1064)
> 	at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:117)
> 	at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
> 	at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:370)
> 	... 16 more
> 
> -------------------