Commit Graph

17 Commits

Author SHA1 Message Date
Erik Johnston 3dfc4a08dc
Fix performance regression in `get_users_in_room` (#13972)
Fixes #13942. Introduced in #13575.

Basically, let's only get the ordered set of hosts out of the DB if we need an ordered set of hosts. Since we split the function up the caching won't be as good, but I think it will still be fine as e.g. multiple backfill requests for the same room will hit the cache.
2022-09-30 13:15:32 +01:00
Sean Quah f49f73c0da
Faster room joins: Avoid blocking `/keys/changes` (#13888)
Part of the work for #12993.

Once #12993 is fully resolved, we expect `/keys/changes` to behave
sensibly when joined to a room with partial state.

Signed-off-by: Sean Quah <seanq@matrix.org>
2022-09-23 17:55:15 +01:00
Sean Quah 03c2bfb7f8
Send device list updates out to servers in partially joined rooms (#13874)
Use the provided list of servers in the room from the `/send_join`
response, since we will not know which users are in the room.  This
isn't sufficient to ensure that all remote servers receive the right
device list updates, since the `/send_join` response may be inaccurate
or we may calculate the membership state of new users in the room
incorrectly.

Signed-off-by: Sean Quah <seanq@matrix.org>
2022-09-23 13:44:03 +01:00
reivilibre d3d9ca156e
Cancel the processing of key query requests when they time out. (#13680) 2022-09-07 12:03:32 +01:00
Eric Eastwood 51d732db3b
Optimize how we calculate `likely_domains` during backfill (#13575)
Optimize how we calculate `likely_domains` during backfill because I've seen this take 17s in production just to `get_current_state` which is used to `get_domains_from_state` (see case [*2. Loading tons of events* in the `/messages` investigation issue](https://github.com/matrix-org/synapse/issues/13356)).

There are 3 ways we currently calculate hosts that are in the room:

 1. `get_current_state` -> `get_domains_from_state`
    - Used in `backfill` to calculate `likely_domains` and `/timestamp_to_event` because it was cargo-culted from `backfill`
    - This one is being eliminated in favor of `get_current_hosts_in_room` in this PR 🕳
 1. `get_current_hosts_in_room`
    - Used for other federation things like sending read receipts and typing indicators
 1. `get_hosts_in_room_at_events`
    - Used when pushing out events over federation to other servers in the `_process_event_queue_loop`

Fix https://github.com/matrix-org/synapse/issues/13626

Part of https://github.com/matrix-org/synapse/issues/13356

Mentioned in [internal doc](https://docs.google.com/document/d/1lvUoVfYUiy6UaHB6Rb4HicjaJAU40-APue9Q4vzuW3c/edit#bookmark=id.2tvwz3yhcafh)


### Query performance

#### Before

The query from `get_current_state` sucks just because we have to get all 80k events. And we see almost the exact same performance locally trying to get all of these events (16s vs 17s):
```
synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 16035.612 ms (00:16.036)

synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 4243.237 ms (00:04.243)
```

But what about `get_current_hosts_in_room`: When there is 8M rows in the `current_state_events` table, the previous query in `get_current_hosts_in_room` took 13s from complete freshness (when the events were first added). But takes 930ms after a Postgres restart or 390ms if running back to back to back.

```sh
$ psql synapse
synapse=# \timing on
synapse=# SELECT COUNT(DISTINCT substring(state_key FROM '@[^:]*:(.*)$'))
FROM current_state_events
WHERE
    type = 'm.room.member'
    AND membership = 'join'
    AND room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
 count
-------
  4130
(1 row)

Time: 13181.598 ms (00:13.182)

synapse=# SELECT COUNT(*) from current_state_events where room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
 count
-------
 80814

synapse=# SELECT COUNT(*) from current_state_events;
  count
---------
 8162847

synapse=# SELECT pg_size_pretty( pg_total_relation_size('current_state_events') );
 pg_size_pretty
----------------
 4702 MB
```

#### After

I'm not sure how long it takes from complete freshness as I only really get that opportunity once (maybe restarting computer but that's cumbersome) and it's not really relevant to normal operating times. Maybe you get closer to the fresh times the more access variability there is so that Postgres caches aren't as exact. Update: The longest I've seen this run for is 6.4s and 4.5s after a computer restart.

After a Postgres restart, it takes 330ms and running back to back takes 260ms.

```sh
$ psql synapse
synapse=# \timing on
Timing is on.
synapse=# SELECT
    substring(c.state_key FROM '@[^:]*:(.*)$') as host
FROM current_state_events c
/* Get the depth of the event from the events table */
INNER JOIN events AS e USING (event_id)
WHERE
    c.type = 'm.room.member'
    AND c.membership = 'join'
    AND c.room_id = '!OGEhHVWSdvArJzumhm:matrix.org'
GROUP BY host
ORDER BY min(e.depth) ASC;
Time: 333.800 ms
```

#### Going further

To improve things further we could add a `limit` parameter to `get_current_hosts_in_room`. Realistically, we don't need 4k domains to choose from because there is no way we're going to query that many before we a) probably get an answer or b) we give up. 

Another thing we can do is optimize the query to use a index skip scan:

 - https://wiki.postgresql.org/wiki/Loose_indexscan
 - Index Skip Scan, https://commitfest.postgresql.org/37/1741/
 - https://www.timescale.com/blog/how-we-made-distinct-queries-up-to-8000x-faster-on-postgresql/
2022-08-30 01:38:14 -05:00
Sean Quah 84169a82dc
Avoid blocking lazy-loading `/sync`s during partial joins (#13477)
Use a state filter or accept partial state in a few places where we
request state, to avoid blocking.

To make lazy-loading `/sync`s work, we need to provide the memberships
of event senders, which are not guaranteed to be in the room state.
Instead we dig through auth events for memberships to present to
clients. The auth events of an event are guaranteed to contain a
passable membership event, otherwise the event would have been rejected.

Note that this only covers the common code paths encountered during
testing. There has been no exhaustive checking of all sync code paths.

Fixes #13146.

Signed-off-by: Sean Quah <seanq@matrix.org>
2022-08-18 11:53:02 +01:00
Eric Eastwood 0a4efbc1dd
Instrument the federation/backfill part of `/messages` (#13489)
Instrument the federation/backfill part of `/messages` so it's easier to follow what's going on in Jaeger when viewing a trace.

Split out from https://github.com/matrix-org/synapse/pull/13440

Follow-up from https://github.com/matrix-org/synapse/pull/13368

Part of https://github.com/matrix-org/synapse/issues/13356
2022-08-16 12:39:40 -05:00
reivilibre c3516e9dec
Faster room joins: make `/joined_members` block whilst the room is partial stated. (#13514) 2022-08-16 13:16:56 +01:00
Eric Eastwood 92d21faf12
Instrument `/messages` for understandable traces in Jaeger (#13368)
In Jaeger:

 - Before: huge list of uncategorized database calls
 - After: nice and collapsible into units of work
2022-08-03 10:57:38 -05:00
Sean Quah 224d792dd7
Refactor `_resolve_state_at_missing_prevs` to return an `EventContext` (#13404)
Previously, `_resolve_state_at_missing_prevs` returned the resolved
state before an event and a partial state flag. These were unwieldy to
carry around would only ever be used to build an event context. Build
the event context directly instead.

Signed-off-by: Sean Quah <seanq@matrix.org>
2022-08-01 13:53:56 +01:00
Sean Quah 335ebb21cc
Faster room joins: avoid blocking when pulling events with missing prevs (#13355)
Avoid blocking on full state in `_resolve_state_at_missing_prevs` and
return a new flag indicating whether the resolved state is partial.
Thread that flag around so that it makes it into the event context.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
2022-07-26 12:39:23 +01:00
Erik Johnston 0731e0829c
Don't pull out the full state when storing state (#13274) 2022-07-15 12:59:45 +00:00
Richard van der Hoff 7c6b2204d1
Faster joins: add issue links to the TODOs (#13004)
... to help us keep track of these things
2022-06-09 10:13:03 +00:00
Erik Johnston 44de53bb79
Reduce state pulled from DB due to sending typing and receipts over federation (#12964)
Reducing the amount of state we pull from the DB is useful as fetching state is expensive in terms of DB, CPU and memory.
2022-06-06 16:46:11 +01:00
Erik Johnston e3163e2e11
Reduce the amount of state we pull from the DB (#12811) 2022-06-06 09:24:12 +01:00
Erik Johnston 888a29f412
Wait for lazy join to complete when getting current state (#12872) 2022-06-01 16:02:53 +01:00
Erik Johnston 1e453053cb
Rename storage classes (#12913) 2022-05-31 12:17:50 +00:00