Weird Error: CLOSE BY CLIENT STACK TRACE

Question

Hi all I have a web application which use Hibernate to retrieve data in the database. And in the server side some execeptions come out at regular interval. Below is the exception logs.

    16:04:22,227 DEBUG NewPooledConnection:491 - com.mchange.v2.c3p0.impl.NewPooledConnection@ef46613 closed by a client.
    java.lang.Exception: DEBUG -- CLOSE BY CLIENT STACK TRACE
        at com.mchange.v2.c3p0.impl.NewPooledConnection.close(NewPooledConnection.java:491)
        at com.mchange.v2.c3p0.impl.NewPooledConnection.close(NewPooledConnection.java:191)
        at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.destroyResource(C3P0PooledConnectionPool.java:470)
        at com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask.run(BasicResourcePool.java:964)
        at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    16:09:42,310 DEBUG C3P0PooledConnectionPool:476 - Successfully destroyed PooledConnection: com.mchange.v2.c3p0.impl.NewPooledConnection@32ef0763
    16:09:42,310 DEBUG BasicResourcePool:967 - Successfully destroyed resource: com.mchange.v2.c3p0.impl.NewPooledConnection@32ef0763
    16:09:42,310 DEBUG GooGooStatementCache:319 - ENTER METHOD: closeAll( org.postgresql.jdbc4.Jdbc4Connection@42df0af8 )! -- num_connections: 1

Could anyone helps me with this problem? Thanks a lot!

Eremite

Answer 1

This is the code that triggers this log statement in C3P0:

if ( logger.isLoggable( MLevel.FINEST ) )
  logger.log( MLevel.FINEST, this + " closed by a client.", 
            new Exception("DEBUG -- CLOSE BY CLIENT STACK TRACE") );

Note that:

1. This is not an exception, the new Exception is used merely to show execution path for debug purposes.

2. And yes, this is only a debug message (actually, FINEST is the lowest possible level in java.util.logging).

To wrap this up: ignore and tune your logging levels to skip these.

Schaffel

Could you please give more details about ignore and tune your logging levels ? – Eremite

Sure. Depending on which logging framework you use you need to configure the logging level of com.mchange.v2.c3p0 logger. Documentation how to do this for: Log4J, Logback or java.util.logging. – Schaffel

@TomaszNurkiewicz which logger should I use? I use Log4j of Apache, but that doesn't have isLoggable method. I've posted a new question #35763971 – Wiesbaden

Answer 2

I found where the error is: I think that it appears when some object calls deliberately

com.mchange.v2.c3p0.ComboPooledDataSource.close

I have configured this class in spring. When I put destroy-method="close" the error appears.

Obviously, I've removed it and the problem is now solved.

Heer

Answer 3

Hibernate connection close work like this way so you no need remove the destroy-method="close".

public synchronized void close() throws SQLException
{
  close(null);
}

private void close(Throwable cause) throws SQLException
{
<--statement-->
if(cause == null)
{
 invalidatingException = NORMAL_CLOSE_PLACEHOLDER;
 if(logger.isLoggable(MLevel.FINEST))
 logger.log(MLevel.FINEST, this + " closed by a client.", new Exception("DEBUG -- CLOSE BY CLIENT STACK TRACE"));
<--statement-->
}

Aut