Fix the issues with scheduling procedures #3816
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Centril
approved these changes
Dec 4, 2025
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Description of Changes
This reapplies the patch from #3704, and fixes the issues that were causing it to deadlock.
The reason it was deadlocking was that it allowed for the following sequence of events:
SchedulerActor::handle_queued()begins mutable txModuleHost::disconnect_client()submits call tocall_reducer(tx: None)call_reducer(tx: Some)WasmModuleInstance::disconnect_clientnow has to try to take tx lock, but the scheduler's call_reducer already holds it and is behind it in the queueSo, I moved most of the logic from
handle_queuedback to being executed in the module worker thread, but kept the code inscheduler.rsso that it can all be reasoned about locally.Fixes #3645. Should I uncomment the implementation of
ExportFunctionForScheduledTable for F: Procedurenow?Expected complexity level and risk
2 - there's a chance that this patch hasn't fully fixed the deadlock issue from #3704, but I'm quite confident.
Testing
while true; do python -m smoketests schedule_reducer -k test_scheduled_table_subscription; donewould freeze up in only 2 or 3 iterations, but now it can run for 10 minutes without issues.