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go/test/fixedbugs/issue54343.go
Matthew Dempsky 8743198152 test: make issue54343.go robust against the tiny allocator
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>
2022-08-11 20:13:07 +00:00

46 lines
695 B
Go

// run
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "runtime"
func main() {
if wait() {
panic("GC'd early")
}
m = nil
if !wait() {
panic("never GC'd")
}
}
var m = New[int]().M
func New[X any]() *T[X] {
p := new(T[X])
runtime.SetFinalizer(p, func(*T[X]) { close(done) })
return p
}
type T[X any] [4]int // N.B., [4]int avoids runtime's tiny object allocator
func (*T[X]) M() {}
var done = make(chan int)
func wait() bool {
for i := 0; i < 10; i++ {
runtime.GC()
select {
case <-done:
return true
default:
}
}
return false
}