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8743198152
I structured the test for issue54343.go after issue46725.go, where I was careful to use `[4]int`, which is a type large enough to avoid the tiny object allocator (which interferes with finalizer semantics). But in that test, I didn't note the importance of that type, so I mistakenly used just `int` in issue54343.go. This CL switches issue54343.go to use `[4]int` too, and then adds comments to both pointing out the significance of this type. Updates #54343. Change-Id: I699b3e64b844ff6d8438bbcb4d1935615a6d8cc4 Reviewed-on: https://go-review.googlesource.com/c/go/+/423115 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Matthew Dempsky <mdempsky@google.com> Reviewed-by: David Chase <drchase@google.com>
49 lines
818 B
Go
49 lines
818 B
Go
// run
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import "runtime"
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type T [4]int // N.B., [4]int avoids runtime's tiny object allocator
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//go:noinline
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func g(x []*T) ([]*T, []*T) { return x, x }
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func main() {
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const Jenny = 8675309
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s := [10]*T{{Jenny}}
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done := make(chan struct{})
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runtime.SetFinalizer(s[0], func(p *T) { close(done) })
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var h, _ interface{} = g(s[:])
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if wait(done) {
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panic("GC'd early")
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}
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if h.([]*T)[0][0] != Jenny {
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panic("lost Jenny's number")
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}
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if !wait(done) {
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panic("never GC'd")
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}
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}
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func wait(done <-chan struct{}) bool {
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for i := 0; i < 10; i++ {
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runtime.GC()
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select {
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case <-done:
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return true
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default:
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}
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}
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return false
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}
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