Change to dynamic select #4
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@@ Coverage Diff @@
## main #4 +/- ##
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Coverage 100.00% 100.00%
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Files 3 3
Lines 206 207 +1
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+ Hits 206 207 +1
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benjivesterby
approved these changes
Mar 22, 2022
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@ghjm Thank you so much for this! I didn't know about this method before.
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Benchmark update from my local test: name old time/op new time/op delta
_Distribute-16 2.86µs ± 2% 1.71µs ± 0% ~ (p=0.400 n=4+1) |
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Description
This PR changes the implementation of
Distribute()to use a dynamically generated select via the reflect package, instead of randomly choosing a single channel to send to.In the case where all "out" channels are available to receive a message, the behavior is the same: the channel is selected pseudo-randomly. However, the pseudo-random choice is made inside the Go library's
selectimplementation, which is presumably highly optimized for this purpose.Benchmark_Distribute-8performance is roughly doubled on my system (831 ns/op after the change vs. 1582 ns/op before).In the case where some of the "out" channels are not able to receive a message right now, the
selectcall will immediately choose one of the available channels. IfDistribute()is being used to send units of work to a pool of workers, we avoid the case where some workers sit idle because we happened to choose a busy worker to receive the next unit.No changes are made to the library API and this should be fully backwards compatible with all library users, unless they rely on the exact details of the channel selection (and it's hard to see how one would do this).