Monitoring for long running transactions

[Samuel Smith <pgsql@xxxxxxxxxx>]

We had a customer complaining of random data loss for the last 6 months 
or so. We eventually tracked it down to a combination of bad coding and 
a couple of bugs with the ORM. Basically, 'BEGIN' was being emitted by 
the web app when viewing a certain page and 'COMMIT' was never emitted 
after that. So once the app would get restarted, all data changes would 
be lost. Definitely worst case scenario.

So the question is, what is the best way to monitor for this scenario 
going forward? Are there any plugins or community recommended scripts 
already made?

Regards,