R1:d84f866ca061

When search indexers contend for a lock, just yield

Summary:
Depends on D19503. Ref T13151. See PHI719. If you have something like a script which updates an object in a loop, we can end up queueing many search reindex tasks.

These tasks may reasonably contend for the lock, especially if the object is larger (lots of text and/or lots of comments) and indexing takes a few seconds.

This isn't concerning, and the indexers should converge to good behavior quickly once the updates stop.

Today, they'll spew a…