gcc/testsuite/go.test/test/deferfin.go

   1 // run
   2
   3 // Copyright 2013 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 // Test that defers do not prevent garbage collection.
   8
   9 package main
  10
  11 import (
  12         "runtime"
  13         "sync"
  14         "sync/atomic"
  15         "time"
  16 )
  17
  18 var sink func()
  19
  20 func main() {
  21         // Does not work on 32-bits due to partially conservative GC.
  22         // Try to enable when we have fully precise GC.
  23         if runtime.GOARCH != "amd64" {
  24                 return
  25         }
  26         // Likewise for gccgo.
  27         if runtime.Compiler == "gccgo" {
  28                 return
  29         }
  30         N := 10
  31         count := int32(N)
  32         var wg sync.WaitGroup
  33         wg.Add(N)
  34         for i := 0; i < N; i++ {
  35                 go func() {
  36                         defer wg.Done()
  37                         v := new(string)
  38                         f := func() {
  39                                 if *v != "" {
  40                                         panic("oops")
  41                                 }
  42                         }
  43                         if *v != "" {
  44                                 // let the compiler think f escapes
  45                                 sink = f
  46                         }
  47                         runtime.SetFinalizer(v, func(p *string) {
  48                                 atomic.AddInt32(&count, -1)
  49                         })
  50                         defer f()
  51                 }()
  52         }
  53         wg.Wait()
  54         for i := 0; i < 3; i++ {
  55                 time.Sleep(10 * time.Millisecond)
  56                 runtime.GC()
  57         }
  58         if count != 0 {
  59                 println(count, "out of", N, "finalizer are not called")
  60                 panic("not all finalizers are called")
  61         }
  62 }
  63