_run_once awaited _subscribe_all_users() inline, before starting the
header/scripthash consumer tasks, and that method subscribed one user
at a time. At thousands of users that's thousands of sequential
round-trips during which nothing else ran: tip_height was frozen and
an in-flight draw's _wait_for_next_block made zero progress for the
entire resubscribe - a reconnect (which the listener already treats as
routine, not exceptional) could stall the lottery for minutes.
_subscribe_all_users now fans out with bounded concurrency
(asyncio.Semaphore, 20 at a time) instead of a serial loop, and one
user's failure no longer stops the rest. _run_once now starts it as
its own background task, created after the consumer tasks rather than
awaited before them, so tip updates and already-subscribed users'
notifications keep flowing throughout - its own completion is
deliberately not raced against the session-ending tasks (unlike them,
it's expected to finish normally), and its failure is logged the same
way address_for_new_user's background task is (B-30).
Left out: decoupling the listunspent refresh from the subscribe call
itself (the third part of the proposed fix) - the periodic
DepositReconciler (B-30) already provides a backstop for a slow or
delayed initial refresh, so the added complexity wasn't worth it here.
Suite grows from 182 to 185 tests, including an end-to-end test
against _run_once proving a new tip is processed while a slow
resubscribe is still in flight. BUGS.md moves B-31 to Previously
fixed.
davide
12df04178e