Deployment instructions: I think all the queue workers get
restarted automatically, so there is probably nothing special
to do here in the deploy itself, but we will want to monitor
it closely, and the change should make our number of locks go
down.
QueueProcessingWorker.start() now calls consume_and_commit(),
which ensures that we don't hold locks after work actions
by using Django's commit_on_success() decorator.
Obviously, workers that override start() will not call consume_and_commit()
through this code path. SlowQueryWorker calls commit_on_success()
in its start() method now, and I hope to address MissedMessageWorker soon.
(imported from commit f3f38a7f45730eee8f3b5794371ba5b994017676)
Use the commit_on_success() context manager around the call
to internal_send_message() inside of SlowQueryWorker's polling
loop, so that the pending SELECT statement from
get_status_dict_by_realm() gets committed. If we don't do
this, postgres will hold locks on zerver_userprofile, and other
tables, for a long time, which can interfere with migrations.
This is an interim solution until we switch postgres's default
commit behavior. Right now the default transaction isolation
is "read committed," so SELECT statements lead to AccessShareLocks
that do no get closed until the transaction finishes.
(imported from commit f72aeffbbe71a731e327459f15bd7dbebaf9e0b8)
Handled by the queue processor for signups. Added a management command
that accomplishes the same task, in case it's needed for manually added users,
or in case we goof and need to remove queued emails for a given user.
This addresses Trac #1807
(imported from commit 6727b82a07fa6a3ea3d827860c9e60fd0602297a)
Steve Howell
acrefoot
Leo Franchi
Zev Benjamin