Forum OpenACS Q&A: Re: OpenACS and Database Locks - Conflict?
You say during the hang you observed "some locks on some tables". Well, what tables? And what code was taking those locks?
As others have suggested above, so far there is also little reason to believe that database locks have anything to do with your problem. They might, they might not. Verify that your AOLserver thread settings are correct. Use that AOLserver nstelemetry page to check for any suspicious AOLserver locks during the hang.
That 9 seconds taken by that scheduled proc seems suspicious. What proc is that, and what is it doing? Instrument all your scheduled procs if necessary in order to find out. Even it turns out to be un-related to your hanging problem, you probably should fix it anyway. Either speed up the scheduled proc, or give it its own thread to run in.