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docs: fix example for channel, do not assume a single-threaded dispatcher #4417

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docs: fix example for channel, do not assume a single-threaded dispatcher #4417

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@murfel murfel commented Apr 21, 2025 •
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This example illustrating when send suspends works on a single-threaded dispatcher, but is send guaranteed to suspend on a multithreaded dispatcher?

val channel = Channel<Int>()
launch {
    check(channel.receive() == 5)
}
channel.send(5) // suspends until 5 is received

dkhalanskyjb
dkhalanskyjb requested changes Apr 22, 2025
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The example could indeed benefit from more comments. To answer your question: it is guaranteed in all scenarios, because the default argument for the channel's buffer size is RENDEZVOUS, which means no buffer gets created. Could you add something like // a channel without a buffer to the code?

I don't understand how delay(100) helps, though.

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murfel commented Jul 7, 2025

Discussed that suspends in the docs should be interpreted as may or may not suspend, but is a suspension point, and the user shouldn't think or base their code on whether the function will actually suspend, hence it is counterproductive to sprinkle the doc snippets with yield().

@murfel murfel closed this Jul 7, 2025
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