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https://issues.apache.org/jira/browse/DBCP-398?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13664259#comment-13664259
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Sarvesh Sakalanaga commented on DBCP-398:
-----------------------------------------
Unfortunately it’s not that easy to write a unit test that can do this. If you
are using sql server and Data nucleus as your ORM (or any client that uses
PoolableConnection) then you can do something like this to repro the bug.
1) Take table exclusive connection lock
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
GO
BEGIN TRANSACTION
UPDATE sds
SET CD_ID = CD_ID
WAITFOR DELAY '00:06:00' -- 6 minutes hh:mm:ss
ROLLBACK TRANSACTION
GO
2) Connect to the server using the client that used PoolableConnection
3) You should see the connections when you do : SELECT * FROM
sys.dm_exec_sessions
4) Execute some query on the table. EG: Select * from sds;
5) Execute "Kill XXX" (replace XXX with spid) to kill the connections. This
should close the underlyingconnection but the PoolableConnection will not be
closed.
6) Call IsClosed on PoolableConnection. (BUG as it returns true);
7) Since IsClosed returns true the client will never call Close and the object
is not release to pool.
Hope this helps!
> DBCP hangs on common pool borrowObject when PoolableConnection is used and
> the underlying connection closed unexpectedly (connection resets/timouts)
> ----------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: DBCP-398
> URL: https://issues.apache.org/jira/browse/DBCP-398
> Project: Commons Dbcp
> Issue Type: Bug
> Reporter: Sarvesh Sakalanaga
>
> The bug is in org.apache.commons.dbcp.PoolableConnection as isClosed method
> on this calls super.isClosed which returns true (as
> DelegatingConnection::isClosed { _closed || _conn.isClosed() }). Since
> PoolableConnection needs to release objects to pool even if the underlying
> connection is closed the isClosed method should be overridden in this class
> and should return _closed. This _closed is the delegating connection close
> which will be set to false even if the underlying connection is closed
> (_conn.isClosed). The fix should also not throw on PoolableConnection::Close
> method if underlying connection is closed as this state is a valid state and
> is expected.
> Also currently the way it stands the clients of PoolableConnection will/may
> not call Close() as isClosed always returns true in this case.
> Below is the stack that the thread hangs on:
> ◾waiting on <0x00000007b5a50e48> (a
> org.apache.commons.pool.impl.GenericObjectPool$Latch)
> at java.lang.Object.wait(Object.java:503)
> at
> org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1104)
> ◾locked <0x00000007b5a50e48> (a
> org.apache.commons.pool.impl.GenericObjectPool$Latch)
> at
> org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
> at
> org.datanucleus.store.rdbms.ConnectionProviderPriorityList.getConnection(ConnectionProviderPriorityList.java:57)
> at
> org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:354)
> at
> org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getXAResource(ConnectionFactoryImpl.java:314)
> at
> org.datanucleus.store.connection.ConnectionManagerImpl.enlistResource(ConnectionManagerImpl.java:386)
> at
> org.datanucleus.store.connection.ConnectionManagerImpl.allocateConnection(ConnectionManagerImpl.java:252)
> at
> org.datanucleus.store.connection.AbstractConnectionFactory.getConnection(AbstractConnectionFactory.java:60)
> at
> org.datanucleus.store.AbstractStoreManager.getConnection(AbstractStoreManager.java:449)
> at
> org.datanucleus.store.AbstractStoreManager.getConnection(AbstractStoreManager.java:418)
> at
> org.datanucleus.store.rdbms.query.JDOQLQuery.performExecute(JDOQLQuery.java:595)
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