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Source file test/init1.go

Documentation: test

  // run
  
  // Copyright 2011 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.
  
  // Test that goroutines and garbage collection run during init.
  
  package main
  
  import "runtime"
  
  var x []byte
  
  func init() {
  	c := make(chan int)
  	go send(c)
  	<-c
  
  	const N = 1000
  	const MB = 1 << 20
  	b := make([]byte, MB)
  	for i := range b {
  		b[i] = byte(i%10 + '0')
  	}
  	s := string(b)
  
  	memstats := new(runtime.MemStats)
  	runtime.ReadMemStats(memstats)
  	sys, numGC := memstats.Sys, memstats.NumGC
  
  	// Generate 1,000 MB of garbage, only retaining 1 MB total.
  	for i := 0; i < N; i++ {
  		x = []byte(s)
  	}
  
  	// Verify that the garbage collector ran by seeing if we
  	// allocated fewer than N*MB bytes from the system.
  	runtime.ReadMemStats(memstats)
  	sys1, numGC1 := memstats.Sys, memstats.NumGC
  	if sys1-sys >= N*MB || numGC1 == numGC {
  		println("allocated 1000 chunks of", MB, "and used ", sys1-sys, "memory")
  		println("numGC went", numGC, "to", numGC1)
  		panic("init1")
  	}
  }
  
  func send(c chan int) {
  	c <- 1
  }
  
  func main() {
  }
  

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