Each push notification carries the subscriber's unread room count as its
badge. The pool built it per subscription, loading the user and counting
their unread memberships: two queries for every subscriber, all in the job
before the deliveries reach the threads. With 1,000 subscribed members the
job spent ~180 ms and 2,000 queries there; with 5,000, a second.
The pool now counts the unread rooms of a whole batch with one grouped query
and hands each subscription its badge; nothing else in the notification needs
the user. The queries still run before the work is posted to the threads,
which run outside the Rails executor. Push::Subscription#notification still
counts by itself when no badge is given, as for the test notification.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0142qgjggdJ2KDdGk7RF9Xm9
Marcello Costagliola