After some pondering about why the database might be locked so
frequently, this is what I've managed to come up with. The first patch
is the most likely to actually help with that, and the others mostly
involve improving robustness.

Ideally we'd come up with a test to quantify how much these kinds of
changes affect contention over the database. For now, though, all that I
can think of is seeing how this affects the systems that have had issues
with that.

- reepca