Gerrit threads have been getting stuck behind a single thread SendEmail
The only way to resolve this issue is to restart Gerrit.
This issue is superficially similar to T131189; however:
- send-email doesn't show up in gerrit show-queue -w --by-queue (tried using various flags)
- lsof for the gerrit process at the time of these problems didn't show any smtp connections
I've tried killing the offending thread via the JavaMelody interface to no avail.
Ongoing upstream discussion: https://groups.google.com/forum/#!msg/repo-discuss/pBMh09-XJsw/vuhDiuTWAAAJ