Rollback SQLAlchemy session after each celery Task

[joar]

In the WSGI app we do a "​rollback" on our SQLAlchemy session after each request.

We should do this for our celeryd tasks too to prevent the session being locked after an SQLAlchemy ProgrammingError or similar. A good place to put it might be in a ​Task.after_return() method of our ​ProcessMedia Task implementation.

[Elrond]

Please consider to use mg_globals.db.reset_after_request() for this. So that we have a common place for those "reset the session" things.

[Christopher Allan Webber]

Moving to 0.4.1

[Christopher Allan Webber]

We're getting close to 0.7.0 so I'm moving this over one.

But in 0.8.0! We're going to get it this time. :)

[Christopher Allan Webber]

Also, even though this is not going in 0.7.0, this is *really important*. Not having this happen may mean needing to restart postgres at various points, which is just Not Nice (TM).

[Elrond]

This one is affecting us, actually.

At least we have users with open transactions in their postgresql pg_stat_activity. And this is not helping in diagnosing real database problems (because we are not able to find the root cause).

So raising to blocker for 0.8.
And confirming.

[Christopher Allan Webber]

See bugs #973 and #974.

Additionally, some of the open transactions have been fixed in git master, by commenting out database up-to-date checking (hence #973).

[Jessica Tallon]

I have added the reset_after_request() call to both on_return which only calls if we're not in eager mode and on_fail so that if we are in eager mode but it fails then we still get the reset. This has been ​fbb3ee5.

If you are still having this issue please re-open this.