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https://issues.apache.org/jira/browse/BEAM-4765?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16720682#comment-16720682
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Robert Burke commented on BEAM-4765:
------------------------------------
[https://github.com/apache/beam/pull/7161] Opted to generate closurized
wrappers for methods instead of going with explicit receiver passing at the
call sites. Closing this.
> Use explicit receivers for method invocations.
> -----------------------------------------------
>
> Key: BEAM-4765
> URL: https://issues.apache.org/jira/browse/BEAM-4765
> Project: Beam
> Issue Type: Sub-task
> Components: sdk-go
> Reporter: Robert Burke
> Assignee: Robert Burke
> Priority: Major
> Fix For: Not applicable
>
>
> Presently we use the "receiverless" variant to reflectively get methods on
> structs in graph/fn.go, but it's possible to get a version with an explicit
> receiver as well. Unfortunately due to reflect method invocation overhead,
> calls to functions sourced this way have significant overhead.
>
> This task represents a TODO in graph/fn.go
>
> I wrote a benchmark (to be submitted) that explores the approaches:
> BenchmarkStructMethodCalls/ReflectCallNoReceiver-12 5000000 377
> ns/op 56 B/op 3 allocs/op
> BenchmarkStructMethodCalls/ReflectCallWithReceiver-12 5000000 297
> ns/op 48 B/op 2 allocs/op
> BenchmarkStructMethodCalls/DirectWithReceiver-12 300000000
> 3.58 ns/op 0 B/op 0 allocs/op
> BenchmarkStructMethodCalls/TypeAssertedWithReceiver-12 300000000
> 3.58 ns/op 0 B/op 0 allocs/op
> BenchmarkStructMethodCalls/ReflectXCallWithReceiver-12 5000000
> 345 ns/op 112 B/op 5 allocs/op
> BenchmarkStructMethodCalls/ShimedCallWithReceiver-12 20000000
> 69.3 ns/op 40 B/op 3 allocs/op
> BenchmarkStructMethodCalls/ShimedCall1x1-12 100000000
> 20.7 ns/op 8 B/op 1 allocs/op
>
> Note: Some of these represent the compiler assisting the explicit calls, due
> to the micro benchmarking: DirectWithReceiver, and TypeAssertedWithReceiver
> in particular.
>
> ShimedCallWithReceiver represents the "typical" invocation path with a
> reflectx.Func.Call([]interface{}) invocation, while ShimedCall1x1 is the
> arity specialized version.
> Note: This be a breaking change to anyone using the reflectx & graph packages
> on structural DoFn outside of the project. However, we don't presently make a
> stability guarantee on these internal package details, so that's probably OK.
>
>
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