cmd/vet: Add check for channels that must be buffered #9399
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Change https://golang.org/cl/274332 mentions this issue: |
This was referenced Dec 1, 2020
Change https://golang.org/cl/274352 mentions this issue: |
Change https://golang.org/cl/274393 mentions this issue: |
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Unbuffered channels passed into signal.Notify can be lost as the docs for signal.Notify caution with: Package signal will not block sending to c: the caller must ensure that c has sufficient buffer space to keep up with the expected signal rate. For a channel used for notification of just one signal value, a buffer of size 1 is sufficient. Found by a static analyzer from Orijtech, Inc. called "sigchanyzer", but it'll be donated to the Go project soon. Updates #9399. Change-Id: Ia0690e447582da028694ed65ace7b97961997b84 Reviewed-on: https://go-review.googlesource.com/c/go/+/274332 Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com> Trust: Emmanuel Odeke <emmanuel@orijtech.com> Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Bryan C. Mills <bcmills@google.com> Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com> TryBot-Result: Go Bot <gobot@golang.org>
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This if follow up of CL 274332. Updates #9399. Change-Id: Ic6dd534dc18227a799cbb9577979f2285596b825 Reviewed-on: https://go-review.googlesource.com/c/go/+/274393 Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com> Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
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There are at least two places in the standard library where channels must have a non-zero buffer in order for the program to be correct:
os.Signal
channels passed tosignal.Notify
.*rpc.Call
channels passed toClient.Go
innet/rpc
.I propose a vet check that ensures that these channels are buffered.
I took a quick look at @rsc's pubgo dataset (circa early 2013), and in the code that compiles, I found 161 calls to
make(chan os.Signal)
of which 61 were unbuffered. I do not have a newer dataset handy (is there one?) but I think it's reasonable to guess that the ratio in newer code would not have changed significantly.I currently have a vet check written that ensures that all calls to
make(os.Signal)
have a non-zero buffer, but this check seems a bit too simplistic, as there may be uses for these channels that do not require a buffer. I think it's safer to require buffered channels to be passed into the mentioned calls. However, I'm not familiar enough with the relevant packages to understand what the best approach for this is.This was originally discussed on the mailing list.
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