This happened if we encountered a stream ordering in `event_push_actions` that had more rows than the batch size of the delete, as If we don't delete any rows in an iteration then the next time round we get the exact same stream ordering and get stuck.
Whenever we want to persist an event, we first compute an event context,
which includes the state at the event and a flag indicating whether the
state is partial. After a lot of processing, we finally try to store the
event in the database, which can fail for partial state events when the
containing room has been un-partial stated in the meantime.
We detect the race as a foreign key constraint failure in the data store
layer and turn it into a special `PartialStateConflictError` exception,
which makes its way up to the method in which we computed the event
context.
To make things difficult, the exception needs to cross a replication
request: `/fed_send_events` for events coming over federation and
`/send_event` for events from clients. We transport the
`PartialStateConflictError` as a `409 Conflict` over replication and
turn `409`s back into `PartialStateConflictError`s on the worker making
the request.
All client events go through
`EventCreationHandler.handle_new_client_event`, which is called in
*a lot* of places. Instead of trying to update all the code which
creates client events, we turn the `PartialStateConflictError` into a
`429 Too Many Requests` in
`EventCreationHandler.handle_new_client_event` and hope that clients
take it as a hint to retry their request.
On the federation event side, there are 7 places which compute event
contexts. 4 of them use outlier event contexts:
`FederationEventHandler._auth_and_persist_outliers_inner`,
`FederationHandler.do_knock`, `FederationHandler.on_invite_request` and
`FederationHandler.do_remotely_reject_invite`. These events won't have
the partial state flag, so we do not need to do anything for then.
The remaining 3 paths which create events are
`FederationEventHandler.process_remote_join`,
`FederationEventHandler.on_send_membership_event` and
`FederationEventHandler._process_received_pdu`.
We can't experience the race in `process_remote_join`, unless we're
handling an additional join into a partial state room, which currently
blocks, so we make no attempt to handle it correctly.
`on_send_membership_event` is only called by
`FederationServer._on_send_membership_event`, so we catch the
`PartialStateConflictError` there and retry just once.
`_process_received_pdu` is called by `on_receive_pdu` for incoming
events and `_process_pulled_event` for backfill. The latter should never
try to persist partial state events, so we ignore it. We catch the
`PartialStateConflictError` in `on_receive_pdu` and retry just once.
Refering to the graph of code paths in
https://github.com/matrix-org/synapse/issues/12988#issuecomment-1156857648
may make the above make more sense.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Cast to postgres types when handling postgres db
* Remove unused method
* Easy annotations
* Annotate create_room
* Use `ParamSpec` to annotate looping_call
* Annotate `default_config`
* Track `now` as a float
`time_ms` returns an int like the proper Synapse `Clock`
* Introduce a `Timer` dataclass
* Introduce a Looper type
* Suppress checking of a mock
* tests.utils is typed
* Changelog
* Whoops, import ParamSpec from typing_extensions
* ditch the psycopg2 casts
==============================
Bugfixes
--------
- Fix unread counts for users on large servers. Introduced in v1.62.0rc1. ([\#13140](https://github.com/matrix-org/synapse/issues/13140))
- Fix DB performance when deleting old push notifications. Introduced in v1.62.0rc1. ([\#13141](https://github.com/matrix-org/synapse/issues/13141))
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Merge tag 'v1.62.0rc2' into develop
Synapse 1.62.0rc2 (2022-07-01)
==============================
Bugfixes
--------
- Fix unread counts for users on large servers. Introduced in v1.62.0rc1. ([\#13140](https://github.com/matrix-org/synapse/issues/13140))
- Fix DB performance when deleting old push notifications. Introduced in v1.62.0rc1. ([\#13141](https://github.com/matrix-org/synapse/issues/13141))
When we receive an event over federation during a faster join, there is no need
to wait for full state, since we have a whole reconciliation process designed
to take the partial state into account.
* Extend the auth rule checks for `m.room.create` events
... and move them up to the top of the function. Since the no auth_events are
allowed for m.room.create events, we may as well get the m.room.create event
checks out of the way first.
* Add a test for create events with prev_events
