We were seeing duplicate cursor errors which is surprising because our cursor names seem pretty unique.

"qp_cursor_%s_%i_%i" % (id(self), os.getpid(), self.cursors)

This incorporates the id of the QueryProcessor instance, the pid, and an incrementing counter from the instance.

What I think was happening was that the QueryProcessor instance was getting garbage collected before the generator was exhausted, then a new QueryProcessor instance was created with the same address (hence same id).

My suggested fix in #2436 solves this by putting the cursor close statement in a finally: section so that it gets executed when the instance is garbage collected.

I was able to replicate this with the following test code:

test = HasTagTest('hastag *')
pdata = {'build': build}
for i in range(1000):
    res = test.run(pdata)

I set up a build that had a large number of tags and used that for the test. The problem replicated readily. With #2436, the problem stopped.

Commit 1527e40 fixes this issue

Commit 71a891f fixes this issue