Atomikos Forum

Hi,

We have seen an issue where by connections have been reaped whilst in use for a very small period of time (often on milliseconds). This resuls in the database connection being closed and transactions rolling back.

The following code reproduces the problem:

// Set stuff up
TransactionManager txnManager = ...;
AtomikosDataSourceBean xaDataSource = ...;


// Set the reap timeout and maintaince period for the test
xaDataSource.setReapTimeout( 5 );
xaDataSource.setMaintenanceInterval( 1 );

logger.info("\n\nINIT COMPLETE\n\n");

Connection connection;
Statement statement;

// Transaction 1
System.out.println("\n\nSTARTING TRANSACTION 1\n\n");
txnManager.begin();

// Do stuff
connection = xaDataSource.getConnection();
statement = connection.createStatement();
System.out.println("RESULT 1 " + statement.execute("SELECT 1") );

statement.close();
connection.close();

txnManager.commit();
System.out.println("\n\nCOMMITED TRANSACTION 1\n\n");

// Sleep for 6 seconds - now the connection will be reaped
Thread.sleep( 6000 );

// Transaction 2
System.out.println("\n\nSTARTING TRANSACTION 2\n\n");
txnManager.begin();

// Do stuff
connection = xaDataSource.getConnection();

// The connection will be reaped - we need to wait 1 second
// for the maintaince thread to jump in
Thread.sleep( 1000 );

statement = connection.createStatement();

System.out.println("RESULT 2 " + statement.execute("SELECT 1") );


statement.close();
connection.close();

txnManager.commit();
System.out.println("\n\nCOMMITED TRANSACTION 2\n\n");


I think the bug is in ConnectionPool - where the reaping logic checks the connection was returned to the pool more than the reap period, not aquired more than the reap period (around line 190):

// THIS SHOULD BE xpc.getLastTimeAquired();
long lastTimeReleased = xpc.getLastTimeReleased();
boolean inUse = !xpc.isAvailable();
           
long now = System.currentTimeMillis();
if ( inUse && ( ( now - maxInUseTime * 1000 ) > lastTimeReleased ) ) {
  Configuration.logDebug ( this + ": connection in use for more than " + maxInUseTime + "s, reaping it: " + xpc );
  xpc.reap();
}

Thanks for the feedback, I have created an issue for the next release (TransactionsEssentials 3.5.7).