github.com/likebike/go--@v0.0.0-20190911215757-0bd925d16e96/go/src/math/rand/race_test.go (about)

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package rand
     6  
     7  import (
     8  	"sync"
     9  	"testing"
    10  )
    11  
    12  // TestConcurrent exercises the rand API concurrently, triggering situations
    13  // where the race detector is likely to detect issues.
    14  func TestConcurrent(t *testing.T) {
    15  	const (
    16  		numRoutines = 10
    17  		numCycles   = 10
    18  	)
    19  	var wg sync.WaitGroup
    20  	defer wg.Wait()
    21  	wg.Add(numRoutines)
    22  	for i := 0; i < numRoutines; i++ {
    23  		go func(i int) {
    24  			defer wg.Done()
    25  			buf := make([]byte, 997)
    26  			for j := 0; j < numCycles; j++ {
    27  				var seed int64
    28  				seed += int64(ExpFloat64())
    29  				seed += int64(Float32())
    30  				seed += int64(Float64())
    31  				seed += int64(Intn(Int()))
    32  				seed += int64(Int31n(Int31()))
    33  				seed += int64(Int63n(Int63()))
    34  				seed += int64(NormFloat64())
    35  				seed += int64(Uint32())
    36  				seed += int64(Uint64())
    37  				for _, p := range Perm(10) {
    38  					seed += int64(p)
    39  				}
    40  				Read(buf)
    41  				for _, b := range buf {
    42  					seed += int64(b)
    43  				}
    44  				Seed(int64(i*j) * seed)
    45  			}
    46  		}(i)
    47  	}
    48  }