Catching transaction timeouts

I’m working on a script which includes a database transaction and uses a try/except to make sure that the transactions gets rolled back and closed sanely when an exception is caught.

import java.lang.Exception try: txID = system.db.beginTransaction(database, isolationLevel, timeout) < a bunch of database stuff...> system.db.commitTransaction(txID) except java.lang.Exception, err: import StringIO, traceback fp = StringIO.StringIO() traceback.print_exc(file=fp) logger.errorf("err=%", str(err)) logger.errorf("err.getCause()=%s", str(err.getCause())) logger.errorf("fp.getvalue()=%s", fp.getvalue()) system.db.rollbackTransaction(txID) excpet Exception, err: <...similar logging for Python exceptions....> finally: closeTransaction(txID)

The problem I’m having is that when the transaction times out, it is already closed when it reaches the “finally” section of my code. Then I end up getting a new java.lang.Exception for trying to execute system.db.closeTransaction() on a transaction which is already closed. (This is a little confusing to me, as it doesn’t complain when I run system.db.rollbackTransaction() on it before then.)

Is there some way that I can examine the transaction to see if it is still open before I try to close it? Or should I be examining the java.lang.Exception when I catch it to see if the problem was a timeout?

If it’s the latter, any guidelines for how best to be sure it’s a timeout? From the logs I captured, I can see that the cause of the general Exception is a GatewayException, which was itself cause by a SQLException. Either of those could be raised for reasons that aren’t a timeout, though, so I’m not sure what I could do besides parse some of the text. What my logging shows:

ERROR [sharedDbTx-AWT-EventQueue-2] err=java.lang.Exception: Error executing system.db.runPrepUpdate(INSERT INTO (a, b, c) VALUES (?, ?, ?), [1, 2, 3], , f9860da0-3a72-4028-9695-162163c90636, false, false) ERROR [sharedDbTx-AWT-EventQueue-2] err.getCause()=com.inductiveautomation.ignition.client.gateway_interface.GatewayException: Connection Error: Transaction "f9860da0-3a72-4028-9695-162163c90636" is closed. ERROR [sharedDbTx-AWT-EventQueue-2] fp.getvalue()=Traceback (most recent call last): File "<module:shared.db.tx>", line 78, in handleTransaction File "<custom-function saveCheckSheet>", line 24, in saveCheckSheet File "<custom-function saveToCheckSheet>", line 26, in saveToCheckSheet Exception: java.lang.Exception: Error executing system.db.runPrepUpdate(INSERT INTO, b, c) VALUES (?, ?, ?), [1, 2, 3], , f9860da0-3a72-4028-9695-162163c90636, false, false)

I supposed I could parse that and find that the transaction is closed, but that seems a bit of a hack to me. Does anyone have any suggestions for a better approach?


Were you able to fix this issue? Just curious to see how you handled the exception.


I would just nest the closeTransaction in a nested try with a “pass” in the except clause. There’s no further handling you can or should do if that fails.