codekingpro/portable-devtools

1// run2 3// Copyright 2018 The Go Authors. All rights reserved.4// Use of this source code is governed by a BSD-style5// license that can be found in the LICENSE file.6 7package main8 9import (10	"fmt"11	"runtime"12)13 14type HeapObj [8]int6415 16type StkObj struct {17	h *HeapObj18}19 20var n int21var c int = -122 23func gc() {24	// encourage heap object to be collected, and have its finalizer run.25	runtime.GC()26	runtime.GC()27	runtime.GC()28	n++29}30 31func main() {32	f()33	gc() // prior to stack objects, heap object is not collected until here34	if c < 0 {35		panic("heap object never collected")36	}37	if c != 1 {38		panic(fmt.Sprintf("expected collection at phase 1, got phase %d", c))39	}40}41 42func f() {43	var s StkObj44	s.h = new(HeapObj)45	runtime.SetFinalizer(s.h, func(h *HeapObj) {46		// Remember at what phase the heap object was collected.47		c = n48	})49	g(&s)50	gc()51}52 53func g(s *StkObj) {54	gc() // heap object is still live here55	runtime.KeepAlive(s)56	gc() // heap object should be collected here57}58