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runtime/race: Race detector does not detect len(c) / {send,recv}(c) race #11067

randall77 opened this issue Jun 4, 2015 · 2 comments


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The race detector should report a race when one goroutine is reading the length of a channel and another is reading or writing to the channel.

func main() {
    res := make(chan int, 1)
    ch := make(chan bool, 1)
    go func() { ch <- true }()
    go func() { res <- len(ch) }()


@randall77 randall77 added this to the Go1.6 milestone Jun 4, 2015
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bradfitz commented Jun 4, 2015

@mikioh mikioh changed the title Race detector does not detect len(c) / {send,recv}(c) race runtime/race: Race detector does not detect len(c) / {send,recv}(c) race Jun 4, 2015
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dvyukov commented Jun 4, 2015

A single channel may be used in send statements, receive operations, and calls to the built-in functions cap and len by any number of goroutines without further synchronization.

@dvyukov dvyukov closed this as completed Jun 4, 2015
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@rsc rsc unassigned dvyukov Jun 23, 2022
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