event, p2p/simulations/adapters: use buffered channel to avoid goroutine leak #20657
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fjl
requested changes
Feb 12, 2020
event/subscription.go
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| @@ -143,7 +143,7 @@ func (s *resubscribeSub) loop() { | |||
| } | |||
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| func (s *resubscribeSub) subscribe() Subscription { | |||
| subscribed := make(chan error) | |||
| subscribed := make(chan error, 1) | |||
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I think it would be better to fix this case by waiting on the subscribed channel when the subscribe loop exits. This way, Unsubscribe will block until the goroutine running s.fn has exited.
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Actually, I have now applied the fix myself.
| @@ -287,7 +287,7 @@ func (n *ExecNode) Stop() error { | |||
| if err := n.Cmd.Process.Signal(syscall.SIGTERM); err != nil { | |||
| return n.Cmd.Process.Kill() | |||
| } | |||
| waitErr := make(chan error) | |||
| waitErr := make(chan error, 1) | |||
fjl
approved these changes
Feb 12, 2020
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enriquefynn
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Mar 10, 2021
…0657) Co-authored-by: Felix Lange <[email protected]>
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subscribe()in event/subscribe.go andStop()in p2p/simulations/adapters/exec.go share a same problem: some goroutines in these functions will be leaked in certain cases (unsub forsubscribe(), and timeout forStop()).In
subscribe(), the send operationsubscribed <- erron L115 will be blocked forever whenunsubis selected. Thus the child goroutine leaks and always occupies the memory.Adding one buffer to the channel will make the send operation never block the child goroutine,
and it will not change semantic.
The same is true for
Stop().In
Stop(), althoughKill()is called on timeout,I am not sure if the child goroutine will be in the same process or not. Here is the annotation of
Kill(), in /os/exec.go: