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Source file test/init1.go

Documentation: test

     1  // run
     2  
     3  // Copyright 2011 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 goroutines and garbage collection run during init.
     8  
     9  package main
    10  
    11  import "runtime"
    12  
    13  var x []byte
    14  
    15  func init() {
    16  	c := make(chan int)
    17  	go send(c)
    18  	<-c
    19  
    20  	const N = 1000
    21  	const MB = 1 << 20
    22  	b := make([]byte, MB)
    23  	for i := range b {
    24  		b[i] = byte(i%10 + '0')
    25  	}
    26  	s := string(b)
    27  
    28  	memstats := new(runtime.MemStats)
    29  	runtime.ReadMemStats(memstats)
    30  	sys, numGC := memstats.Sys, memstats.NumGC
    31  
    32  	// Generate 1,000 MB of garbage, only retaining 1 MB total.
    33  	for i := 0; i < N; i++ {
    34  		x = []byte(s)
    35  	}
    36  
    37  	// Verify that the garbage collector ran by seeing if we
    38  	// allocated fewer than N*MB bytes from the system.
    39  	runtime.ReadMemStats(memstats)
    40  	sys1, numGC1 := memstats.Sys, memstats.NumGC
    41  	if sys1-sys >= N*MB || numGC1 == numGC {
    42  		println("allocated 1000 chunks of", MB, "and used ", sys1-sys, "memory")
    43  		println("numGC went", numGC, "to", numGC1)
    44  		panic("init1")
    45  	}
    46  }
    47  
    48  func send(c chan int) {
    49  	c <- 1
    50  }
    51  
    52  func main() {
    53  }
    54  

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