benchmark_test.go

Documentation: context

		 1  // Copyright 2014 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 context_test
		 6  
		 7  import (
		 8  	. "context"
		 9  	"fmt"
		10  	"runtime"
		11  	"sync"
		12  	"testing"
		13  	"time"
		14  )
		15  
		16  func BenchmarkCommonParentCancel(b *testing.B) {
		17  	root := WithValue(Background(), "key", "value")
		18  	shared, sharedcancel := WithCancel(root)
		19  	defer sharedcancel()
		20  
		21  	b.ResetTimer()
		22  	b.RunParallel(func(pb *testing.PB) {
		23  		x := 0
		24  		for pb.Next() {
		25  			ctx, cancel := WithCancel(shared)
		26  			if ctx.Value("key").(string) != "value" {
		27  				b.Fatal("should not be reached")
		28  			}
		29  			for i := 0; i < 100; i++ {
		30  				x /= x + 1
		31  			}
		32  			cancel()
		33  			for i := 0; i < 100; i++ {
		34  				x /= x + 1
		35  			}
		36  		}
		37  	})
		38  }
		39  
		40  func BenchmarkWithTimeout(b *testing.B) {
		41  	for concurrency := 40; concurrency <= 4e5; concurrency *= 100 {
		42  		name := fmt.Sprintf("concurrency=%d", concurrency)
		43  		b.Run(name, func(b *testing.B) {
		44  			benchmarkWithTimeout(b, concurrency)
		45  		})
		46  	}
		47  }
		48  
		49  func benchmarkWithTimeout(b *testing.B, concurrentContexts int) {
		50  	gomaxprocs := runtime.GOMAXPROCS(0)
		51  	perPContexts := concurrentContexts / gomaxprocs
		52  	root := Background()
		53  
		54  	// Generate concurrent contexts.
		55  	var wg sync.WaitGroup
		56  	ccf := make([][]CancelFunc, gomaxprocs)
		57  	for i := range ccf {
		58  		wg.Add(1)
		59  		go func(i int) {
		60  			defer wg.Done()
		61  			cf := make([]CancelFunc, perPContexts)
		62  			for j := range cf {
		63  				_, cf[j] = WithTimeout(root, time.Hour)
		64  			}
		65  			ccf[i] = cf
		66  		}(i)
		67  	}
		68  	wg.Wait()
		69  
		70  	b.ResetTimer()
		71  	b.RunParallel(func(pb *testing.PB) {
		72  		wcf := make([]CancelFunc, 10)
		73  		for pb.Next() {
		74  			for i := range wcf {
		75  				_, wcf[i] = WithTimeout(root, time.Hour)
		76  			}
		77  			for _, f := range wcf {
		78  				f()
		79  			}
		80  		}
		81  	})
		82  	b.StopTimer()
		83  
		84  	for _, cf := range ccf {
		85  		for _, f := range cf {
		86  			f()
		87  		}
		88  	}
		89  }
		90  
		91  func BenchmarkCancelTree(b *testing.B) {
		92  	depths := []int{1, 10, 100, 1000}
		93  	for _, d := range depths {
		94  		b.Run(fmt.Sprintf("depth=%d", d), func(b *testing.B) {
		95  			b.Run("Root=Background", func(b *testing.B) {
		96  				for i := 0; i < b.N; i++ {
		97  					buildContextTree(Background(), d)
		98  				}
		99  			})
	 100  			b.Run("Root=OpenCanceler", func(b *testing.B) {
	 101  				for i := 0; i < b.N; i++ {
	 102  					ctx, cancel := WithCancel(Background())
	 103  					buildContextTree(ctx, d)
	 104  					cancel()
	 105  				}
	 106  			})
	 107  			b.Run("Root=ClosedCanceler", func(b *testing.B) {
	 108  				for i := 0; i < b.N; i++ {
	 109  					ctx, cancel := WithCancel(Background())
	 110  					cancel()
	 111  					buildContextTree(ctx, d)
	 112  				}
	 113  			})
	 114  		})
	 115  	}
	 116  }
	 117  
	 118  func buildContextTree(root Context, depth int) {
	 119  	for d := 0; d < depth; d++ {
	 120  		root, _ = WithCancel(root)
	 121  	}
	 122  }
	 123  
	 124  func BenchmarkCheckCanceled(b *testing.B) {
	 125  	ctx, cancel := WithCancel(Background())
	 126  	cancel()
	 127  	b.Run("Err", func(b *testing.B) {
	 128  		for i := 0; i < b.N; i++ {
	 129  			ctx.Err()
	 130  		}
	 131  	})
	 132  	b.Run("Done", func(b *testing.B) {
	 133  		for i := 0; i < b.N; i++ {
	 134  			select {
	 135  			case <-ctx.Done():
	 136  			default:
	 137  			}
	 138  		}
	 139  	})
	 140  }
	 141  
	 142  func BenchmarkContextCancelDone(b *testing.B) {
	 143  	ctx, cancel := WithCancel(Background())
	 144  	defer cancel()
	 145  
	 146  	b.RunParallel(func(pb *testing.PB) {
	 147  		for pb.Next() {
	 148  			select {
	 149  			case <-ctx.Done():
	 150  			default:
	 151  			}
	 152  		}
	 153  	})
	 154  }
	 155
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