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Problems with Go channels (2016)

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159 points mpweiher | 2 comments | 13 Apr 25 05:43 UTC | HN request time: 0.017s | source
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ricardobeat ◴[13 Apr 25 11:22 UTC] No.43671958[source]▶
Strange to go all this length without mentioning the approaches that solve the problem in that first example:

1. send a close message on the channel that stops the goroutine

2. use a Context instance - `ctx.Done()` returns a channel you can select on

Both are quite easy to grasp and implement.

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jtolds ◴[13 Apr 25 11:29 UTC] No.43671984[source]▶
Hi! No, I think you've misunderstood the assignment. The example posits that you have a "game" running, which should end when the last player leaves. While only using channels as a synchronization primitive (a la CSP), at what point do you decide the last player has left, and where and when do you call close on the channel?
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1. aflag ◴[13 Apr 25 12:52 UTC] No.43672431[source]▶
Naive question, can't you just have a player count alongside the best score and leave when that reaches 0?
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2. jtolds ◴[13 Apr 25 18:22 UTC] No.43674754[source]▶
Adding an atomic counter is absolutely a great solution in the real world, definitely, and compare and swap or a mutex or similar totally is what you want to do. In fact, that's my point in that part of the post - you want an atomic variable or a mutex or something there. Other synchronization primitives are more useful than sticking with the CSP idea of only using channels for synchronization.