[jira] [Created] (DBCP-484) Connection leak during XATransaction in high load

["Emanuel Freitas (JIRA)" <ji...@apache.org>]

Emanuel Freitas created DBCP-484:
------------------------------------

             Summary: Connection leak during XATransaction in high load
                 Key: DBCP-484
                 URL: https://issues.apache.org/jira/browse/DBCP-484
             Project: Commons Dbcp
          Issue Type: Bug
    Affects Versions: 2.2.0
            Reporter: Emanuel Freitas


We're experiencing a connection leak in a distributed transaction when the system is under heavy load. We're using commons-dbcp (latest version) + eclipselink and narayana to perform transaction coordination.

From time to time we can see a stacktrace reporting an abandoned connection. We are trying to figure out what's the root cause and we think that might be some issue in the commons dbcp (not sure) . More specifically, this parte of the code:

ManagedConnection#updateTransactionStatus
{code:java}
if (transactionContext != null) {
    if (transactionContext.isActive()) {
        if (transactionContext != transactionRegistry.getActiveTransactionContext()) {
            throw new SQLException("Connection can not be used while enlisted in another transaction");
        }
        return;
    }
    // transaction should have been cleared up by TransactionContextListener, but in
    // rare cases another lister could have registered which uses the connection before
    // our listener is called.  In that rare case, trigger the transaction complete call now
    transactionComplete();    
}{code}
 

If the transactionContext is different than null but the state is not "active" (ex: STATUS_ROLLEDBACK, STATUS_ROLLING_BACK, etc) it executes the transactionComplete mothod that clears the reference to a shared connection and after that the connection is never closed (returned to the pool). 

 

If we move the transactionComplete(); to an else,(see below), the connection leak does not happen.
{code:java}
if (transactionContext != null) {
    if (transactionContext.isActive()) {
        if (transactionContext != transactionRegistry.getActiveTransactionContext()) {
            throw new SQLException("Connection can not be used while enlisted in another transaction");
        }
        return;
    }
} else {
    transactionComplete();
}{code}
 

After this the dbcp unit tests still pass but I'm not sure about this changes. Can you please check?

Thanks

 



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