Fix deadlock and race condition in proposal fetching #2379
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* Change from broadcast channel to multi-consumer channel. This means only one fetcher task will receive each proposal to be fetched, which is the actual behavior we want. Before, with broadcast, we had multiple fetchers always fetching the same proposal, which is why we saw race conditions causing database serialization errors. It should now be possible to reenable multiple workers. * Use an unbounded channel. This prevents a deadlock where a consumer sends back into the channel (e.g. to recursively fetch the parent of the proposal it had just fetched), but the channel is full, blocking the consumer, the very task responsible for clearing the blockage.
jbearer
requested review from
philippecamacho,
ImJeremyHe,
sveitser,
tbro and
imabdulbasit
as code owners
|
Backport failed for Please cherry-pick the changes locally and resolve any conflicts. git fetch origin release-shibainu
git worktree add -d .worktree/backport-2379-to-release-shibainu origin/release-shibainu
cd .worktree/backport-2379-to-release-shibainu
git switch --create backport-2379-to-release-shibainu
git cherry-pick -x 8cd4f976e366c528c8ba6e39a31522dbd70e0344 |
jbearer
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that referenced
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Dec 9, 2024
* Fix deadlock and race condition in proposal fetching * Change from broadcast channel to multi-consumer channel. This means only one fetcher task will receive each proposal to be fetched, which is the actual behavior we want. Before, with broadcast, we had multiple fetchers always fetching the same proposal, which is why we saw race conditions causing database serialization errors. It should now be possible to reenable multiple workers. * Use an unbounded channel. This prevents a deadlock where a consumer sends back into the channel (e.g. to recursively fetch the parent of the proposal it had just fetched), but the channel is full, blocking the consumer, the very task responsible for clearing the blockage. * Add metrics for proposal fetcher
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This PR:
receive each proposal to be fetched, which is the actual behavior we want. Before, with broadcast,
we had multiple fetchers always fetching the same proposal, which is why we saw race conditions
causing database serialization errors. It should now be possible to reenable multiple workers.
(e.g. to recursively fetch the parent of the proposal it had just fetched), but the channel is
full, blocking the consumer, the very task responsible for clearing the blockage.