Re: [c3p0-users] Help: About Database Connection TimeOut

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

hi,

you have checkoutTimeout set, and for a period of at least  
checkoutTimeout the connection pool has been out of Connections and  
unable to acquire one, either from the database or from another client  
checking the Connection back in.

do you kow if your pool is at maxPoolSize when this happens? if so,  
there is probably a Connection leak -- use unreturnedConnectionTimeout  
and debugUnreturnedConnectionStackTraces to find where in your app  
Connections are checked out without reliably being checked in.

if the pool is not at maxPoolSize, then c3p0 is probably unable to  
acquire new Connections from the database. Check your logs for  
messages relating to acquisition failures.

        smiles,
            steve


On Dec 28, 2009, at 6:57 AM, xiaoyu1985ban wrote:

> Hi：
> I am using Spring 2.0 + Hibernate 3.2 + Struts 1.3 in My Projects. I  
> use C3P0 to manage the database connection, and the app server is  
> Tomcat 5.5.26.
> At first it works fine,but after about one month, I just can not  
> connect to the database. The Excepition message is shown as bellow:
>
> Caused by: java.sql.SQLException: An attempt by a client to checkout  
> a Connection has timed out.
>     at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtil s.java:104)
>     at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtil s.java:65)
>     at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.  
> checkoutPooledConnection(C3P0PooledConnectionPool. java:262)
>     at com.mchange.v2.c3p0.PoolBackedDataSource.getConnec  
> tion(PoolBackedDataSource.java:94)
>     at com.mchange.v2.c3p0.ComboPooledDataSource.getConne  
> ction(ComboPooledDataSource.java:521)
>     at org.springframework.orm.hibernate3.LocalDataSource  
> ConnectionProvider.getConnection(LocalDataSourceCo  
> nnectionProvider.java:80)
>     at org.hibernate.jdbc.ConnectionManager.openConnectio  
> n(ConnectionManager.java:315)
>     ... 22 more
> Caused by: com.mchange.v2.resourcepool.TimeoutException: internal --  
> timeout at awaitAcquire()
>     at com.mchange.v2.resourcepool.BasicResourcePool.awai  
> tAcquire(BasicResourcePool.java:970)
>     at com.mchange.v2.resourcepool.BasicResourcePool.chec  
> koutResource(BasicResourcePool.java:208)
>     at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.  
> checkoutPooledConnection(C3P0PooledConnectionPool. java:260)
>     ... 26 more
>
> It seems that C3P0 just can not get database connection. The problem  
> disappears after I restart the server,but after sometime, about one  
> month,
> the problem occurs again.
>
>      I have googled myself for quite a long time, and I found that  
> many people had the same problem with me.But unfortunately, there is  
> no good idea about this problem,so I want to see if I can get any  
> help from you.
>
> Best Wishes !
>
>
>
> 2009-12-28
> xiaoyu1985ban
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