Cleanly shutdown SynapseHomeServer object #18828
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This reverts commit 61508a6.
MadLittleMods
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Sep 29, 2025
| Args: | ||
| deferred: The Deferred to potentially timeout. | ||
| timeout: Timeout in seconds | ||
| cancel_on_shutdown: Whether this call should be tracked for cleanup during |
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Do we still use this anywhere? Why?
Feels like it should be removed
Previous conversation: #18828 (comment)
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Yes. There are two instances of:
# We don't track these calls since they are constantly being
# overridden by new calls to /sync and they don't hold the
# `HomeServer` in memory on shutdown. It is safe to let them
# timeout of their own accord after shutting down since it
# won't delay shutdown and there won't be any adverse
# behvaviour.
One for clock.call_later and one for timeout_deferred that I have found during local testing to not be worth tracking for the reasons mentioned in the comment.
They fire off every time a /sync response finishes (with new data or timeout), which is quite frequently and will scale to massive number of call_later/cancel flip flops on large homeservers such as matrix.org. There is no need to track them since they don't hold a hs ref. I think the tradeoff here of not tracking them is the right call here based on what I have seen while testing.
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| # Register background tasks required by this server. This must be done | ||
| # somewhat manually due to the background tasks not being registered | ||
| # unless handlers are instantiated. | ||
| if self.config.worker.run_background_tasks: | ||
| self.start_background_tasks() |
MadLittleMods
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This was originally removed in #18886 but it looks like it snuck back in #18828 during a [bad merge](4cd3d91). Noticed while looking at Synapse setup and startup (just by happen stance). I don't think this has adverse effects on Synapse actually working and `start_background_tasks()` can be called multiple times. ### Is there a good way to audit all of these merges? As I would like to see the conflicts for each merge. This works but it's still hard to notice anything is wrong: ``` git log --remerge-diff <commit-sha> ``` > shows the difference from mechanical merge result and the result that is actually recorded in a merge commit via https://stackoverflow.com/questions/15277708/how-do-you-see-show-a-git-merge-conflict-resolution-that-was-done-given-a-mer/71181334#71181334 The following better. Specify the version range to the commit right before the merge to the merge. And can even specify which file to look at to make it more obvious with the hindsight we have now. ``` git log --remerge-diff <merge-commit-sha>~1..<merge-commit-sha> -- synapse/server.py ``` Example: ``` git log --remerge-diff 4cd3d91~1..4cd3d91 -- synapse/server.py ```
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This PR aims to allow for a clean shutdown of the
SynapseHomeServerobject so that it can be fully deleted and cleaned up by garbage collection without shutting down the entire python process.Fix https://github.com/element-hq/synapse-small-hosts/issues/50
Pull Request Checklist
EventStoretoEventWorkerStore.".code blocks.