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natsbus: do not close the channel a NATS callback writes to - #153
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Unsubscribe does not wait for a callback that is already running, so its write could send on the closed msgChan and crash the process. Read now returns on context cancel, and Close leaves msgChan open. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
paulwe
approved these changes
Oct 6, 2026
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Closing a plain NATS subscription no longer panics.
Closeunsubscribed and then closedmsgChan(natsbus.go#L163-L168).Unsubscribedoes not wait for a callback that is already running. That callback'swritethen sends on the closed channel and crashes the process. This can happen when an RPC client closes while responses are still arriving, for example during node shutdown.Now
Closedoes not closemsgChan, andReadreturns when the subscription's context is cancelled, as the Redis bus does.A few messages can still be delivered after
Close. A latewritecan add one to the buffer, andReadmay return buffered messages before it reports the close. This also happened before the change:Readreturned the buffered messages first, and the typed subscription can pass them on to its channel after its ownClose.TestSubscriptionWriteAfterClosewrites afterClose. On main it panics.🤖 Generated with Claude Code