We do this by a) not pulling out all membership events, and b) batch
inserting bans.
One blocking concern is that this bypasses the `update_membership`
function, which otherwise all other membership events go via. In this
case it's fine (having audited what it is doing), but I'm hesitant to
set the precedent of bypassing it, given it has a lot of logic in there.
---------
Co-authored-by: Eric Eastwood <erice@element.io>
This PR reverts https://github.com/element-hq/synapse/pull/18751
### Why revert?
@reivilibre
[found](https://matrix.to/#/!vcyiEtMVHIhWXcJAfl:sw1v.org/$u9OEmMxaFYUzWHhCk1A_r50Y0aGrtKEhepF7WxWJkUA?via=matrix.org&via=node.marinchik.ink&via=element.io)
that our CI was failing in bizarre ways (thanks for stepping up to dive
into this 🙇). Examples:
- `twisted.internet.error.ProcessTerminated: A process has ended with a
probable error condition: process ended by signal 9.`
- `twisted.internet.error.ProcessTerminated: A process has ended with a
probable error condition: process ended by signal 15.`
<details>
<summary>More detailed part of the log</summary>
https://github.com/element-hq/synapse/actions/runs/16758038107/job/47500520633#step:9:6809
```
tests.util.test_wheel_timer.WheelTimerTestCase.test_single_insert_fetch
===============================================================================
Error:
Traceback (most recent call last):
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/trial/_dist/disttrial.py", line 371, in task
await worker.run(case, result)
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/trial/_dist/worker.py", line 305, in run
return await self.callRemote(workercommands.Run, testCase=testCaseId) # type: ignore[no-any-return]
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/defer.py", line 1187, in __iter__
yield self
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/defer.py", line 1092, in _runCallbacks
current.result = callback( # type: ignore[misc]
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/protocols/amp.py", line 1968, in _massageError
error.trap(RemoteAmpError)
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/python/failure.py", line 431, in trap
self.raiseException()
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/python/failure.py", line 455, in raiseException
raise self.value.with_traceback(self.tb)
twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended by signal 9.
tests.util.test_macaroons.MacaroonGeneratorTestCase.test_guest_access_token
-------------------------------------------------------------------------------
Ran 4325 tests in 669.321s
FAILED (skips=159, errors=62, successes=4108)
while calling from thread
Traceback (most recent call last):
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/base.py", line 1064, in runUntilCurrent
f(*a, **kw)
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/base.py", line 790, in stop
raise error.ReactorNotRunning("Can't stop reactor that isn't running.")
twisted.internet.error.ReactorNotRunning: Can't stop reactor that isn't running.
joining disttrial worker #0 failed
Traceback (most recent call last):
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/defer.py", line 1853, in _inlineCallbacks
result = context.run(
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/python/failure.py", line 467, in throwExceptionIntoGenerator
return g.throw(self.value.with_traceback(self.tb))
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/trial/_dist/worker.py", line 406, in exit
await endDeferred
File "/home/runner/.cache/pypoetry/virtualenvs/matrix-synapse-pswDeSvb-py3.9/lib/python3.9/site-packages/twisted/internet/defer.py", line 1187, in __iter__
yield self
twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended by signal 15.
```
</details>
With more debugging (thanks @devonh for also stepping in as maintainer),
we were finding that the CI was consistently failing at
`test_exposed_to_prometheus` which was a bit of smoke because of all of
the [metrics
changes](https://github.com/element-hq/synapse/issues/18592) that were
merged recently.
Locally, although I wasn't able to reproduce the bizarre errors, I could
easily see increased memory usage (~20GB vs ~2GB) and the
`test_exposed_to_prometheus` test taking a while to complete when
running a full test run (`SYNAPSE_TEST_LOG_LEVEL=INFO poetry run trial
tests`).
<img width="1485" height="78" alt="Lots of memory usage"
src="https://github.com/user-attachments/assets/811e2a96-75e5-4a3c-966c-00dc0512cea9"
/>
After updating `test_exposed_to_prometheus` to dump the
`latest_metrics_response = generate_latest(REGISTRY)`, I could see that
it's a massive 3.2GB response. Inspecting the contents, we can see 4.1M
(4,137,123) entries for just
`synapse_background_update_status{server_name="test"} 3.0` which is a
`LaterGauge`. I don't think we have 4.1M test cases so it's also unclear
why we end up with so many samples but it does make sense that we do see
a lot of duplicates because each `HomeserverTestCase` will create a
homeserver for each test case that will `LaterGauge.register_hook(...)`
(part of the https://github.com/element-hq/synapse/pull/18751 changes).
`tests/storage/databases/main/test_metrics.py`
```python
latest_metrics_response = generate_latest(REGISTRY)
with open("/tmp/synapse-test-metrics", "wb") as f:
f.write(latest_metrics_response)
```
After reverting the https://github.com/element-hq/synapse/pull/18751
changes, running the full test suite locally doesn't result in memory
spikes and seems to run normally.
### Dev notes
Discussion in the
[`#synapse-dev:matrix.org`](https://matrix.to/#/!vcyiEtMVHIhWXcJAfl:sw1v.org/$vkMATs04yqZggVVd6Noop5nU8M2DVoTkrAWshw7u1-w?via=matrix.org&via=node.marinchik.ink&via=element.io)
room.
### Pull Request Checklist
<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->
* [x] Pull request is based on the develop branch
* [ ] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
- Use markdown where necessary, mostly for `code blocks`.
- End with either a period (.) or an exclamation mark (!).
- Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [ ] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
