831 lines
23 KiB
Go
831 lines
23 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package testing
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import (
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"flag"
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"fmt"
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"internal/race"
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"internal/sysinfo"
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"io"
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"math"
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"os"
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"runtime"
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"sort"
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"strconv"
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"strings"
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"sync"
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"sync/atomic"
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"time"
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"unicode"
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)
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func initBenchmarkFlags() {
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matchBenchmarks = flag.String("test.bench", "", "run only benchmarks matching `regexp`")
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benchmarkMemory = flag.Bool("test.benchmem", false, "print memory allocations for benchmarks")
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flag.Var(&benchTime, "test.benchtime", "run each benchmark for duration `d`")
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}
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var (
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matchBenchmarks *string
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benchmarkMemory *bool
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benchTime = durationOrCountFlag{d: 1 * time.Second} // changed during test of testing package
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)
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type durationOrCountFlag struct {
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d time.Duration
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n int
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allowZero bool
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}
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func (f *durationOrCountFlag) String() string {
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if f.n > 0 {
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return fmt.Sprintf("%dx", f.n)
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}
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return f.d.String()
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}
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func (f *durationOrCountFlag) Set(s string) error {
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if strings.HasSuffix(s, "x") {
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n, err := strconv.ParseInt(s[:len(s)-1], 10, 0)
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if err != nil || n < 0 || (!f.allowZero && n == 0) {
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return fmt.Errorf("invalid count")
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}
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*f = durationOrCountFlag{n: int(n)}
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return nil
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}
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d, err := time.ParseDuration(s)
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if err != nil || d < 0 || (!f.allowZero && d == 0) {
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return fmt.Errorf("invalid duration")
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}
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*f = durationOrCountFlag{d: d}
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return nil
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}
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// Global lock to ensure only one benchmark runs at a time.
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var benchmarkLock sync.Mutex
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// Used for every benchmark for measuring memory.
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var memStats runtime.MemStats
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// InternalBenchmark is an internal type but exported because it is cross-package;
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// it is part of the implementation of the "go test" command.
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type InternalBenchmark struct {
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Name string
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F func(b *B)
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}
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// B is a type passed to Benchmark functions to manage benchmark
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// timing and to specify the number of iterations to run.
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//
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// A benchmark ends when its Benchmark function returns or calls any of the methods
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// FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods must be called
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// only from the goroutine running the Benchmark function.
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// The other reporting methods, such as the variations of Log and Error,
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// may be called simultaneously from multiple goroutines.
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//
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// Like in tests, benchmark logs are accumulated during execution
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// and dumped to standard output when done. Unlike in tests, benchmark logs
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// are always printed, so as not to hide output whose existence may be
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// affecting benchmark results.
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type B struct {
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common
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importPath string // import path of the package containing the benchmark
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context *benchContext
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N int
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previousN int // number of iterations in the previous run
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previousDuration time.Duration // total duration of the previous run
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benchFunc func(b *B)
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benchTime durationOrCountFlag
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bytes int64
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missingBytes bool // one of the subbenchmarks does not have bytes set.
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timerOn bool
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showAllocResult bool
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result BenchmarkResult
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parallelism int // RunParallel creates parallelism*GOMAXPROCS goroutines
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// The initial states of memStats.Mallocs and memStats.TotalAlloc.
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startAllocs uint64
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startBytes uint64
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// The net total of this test after being run.
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netAllocs uint64
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netBytes uint64
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// Extra metrics collected by ReportMetric.
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extra map[string]float64
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}
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// StartTimer starts timing a test. This function is called automatically
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// before a benchmark starts, but it can also be used to resume timing after
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// a call to StopTimer.
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func (b *B) StartTimer() {
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if !b.timerOn {
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runtime.ReadMemStats(&memStats)
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b.startAllocs = memStats.Mallocs
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b.startBytes = memStats.TotalAlloc
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b.start = time.Now()
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b.timerOn = true
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}
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}
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// StopTimer stops timing a test. This can be used to pause the timer
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// while performing complex initialization that you don't
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// want to measure.
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func (b *B) StopTimer() {
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if b.timerOn {
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b.duration += time.Since(b.start)
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runtime.ReadMemStats(&memStats)
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b.netAllocs += memStats.Mallocs - b.startAllocs
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b.netBytes += memStats.TotalAlloc - b.startBytes
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b.timerOn = false
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}
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}
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// ResetTimer zeroes the elapsed benchmark time and memory allocation counters
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// and deletes user-reported metrics.
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// It does not affect whether the timer is running.
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func (b *B) ResetTimer() {
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if b.extra == nil {
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// Allocate the extra map before reading memory stats.
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// Pre-size it to make more allocation unlikely.
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b.extra = make(map[string]float64, 16)
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} else {
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for k := range b.extra {
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delete(b.extra, k)
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}
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}
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if b.timerOn {
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runtime.ReadMemStats(&memStats)
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b.startAllocs = memStats.Mallocs
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b.startBytes = memStats.TotalAlloc
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b.start = time.Now()
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}
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b.duration = 0
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b.netAllocs = 0
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b.netBytes = 0
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}
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// SetBytes records the number of bytes processed in a single operation.
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// If this is called, the benchmark will report ns/op and MB/s.
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func (b *B) SetBytes(n int64) { b.bytes = n }
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// ReportAllocs enables malloc statistics for this benchmark.
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// It is equivalent to setting -test.benchmem, but it only affects the
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// benchmark function that calls ReportAllocs.
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func (b *B) ReportAllocs() {
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b.showAllocResult = true
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}
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// runN runs a single benchmark for the specified number of iterations.
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func (b *B) runN(n int) {
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benchmarkLock.Lock()
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defer benchmarkLock.Unlock()
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defer b.runCleanup(normalPanic)
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// Try to get a comparable environment for each run
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// by clearing garbage from previous runs.
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runtime.GC()
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b.raceErrors = -race.Errors()
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b.N = n
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b.parallelism = 1
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b.ResetTimer()
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b.StartTimer()
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b.benchFunc(b)
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b.StopTimer()
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b.previousN = n
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b.previousDuration = b.duration
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b.raceErrors += race.Errors()
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if b.raceErrors > 0 {
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b.Errorf("race detected during execution of benchmark")
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}
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}
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func min(x, y int64) int64 {
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if x > y {
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return y
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}
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return x
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}
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func max(x, y int64) int64 {
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if x < y {
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return y
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}
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return x
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}
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// run1 runs the first iteration of benchFunc. It reports whether more
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// iterations of this benchmarks should be run.
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func (b *B) run1() bool {
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if ctx := b.context; ctx != nil {
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// Extend maxLen, if needed.
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if n := len(b.name) + ctx.extLen + 1; n > ctx.maxLen {
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ctx.maxLen = n + 8 // Add additional slack to avoid too many jumps in size.
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}
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}
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go func() {
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// Signal that we're done whether we return normally
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// or by FailNow's runtime.Goexit.
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defer func() {
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b.signal <- true
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}()
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b.runN(1)
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}()
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<-b.signal
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if b.failed {
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fmt.Fprintf(b.w, "--- FAIL: %s\n%s", b.name, b.output)
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return false
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}
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// Only print the output if we know we are not going to proceed.
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// Otherwise it is printed in processBench.
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b.mu.RLock()
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finished := b.finished
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b.mu.RUnlock()
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if atomic.LoadInt32(&b.hasSub) != 0 || finished {
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tag := "BENCH"
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if b.skipped {
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tag = "SKIP"
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}
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if b.chatty != nil && (len(b.output) > 0 || finished) {
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b.trimOutput()
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fmt.Fprintf(b.w, "--- %s: %s\n%s", tag, b.name, b.output)
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}
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return false
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}
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return true
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}
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var labelsOnce sync.Once
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// run executes the benchmark in a separate goroutine, including all of its
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// subbenchmarks. b must not have subbenchmarks.
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func (b *B) run() {
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labelsOnce.Do(func() {
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fmt.Fprintf(b.w, "goos: %s\n", runtime.GOOS)
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fmt.Fprintf(b.w, "goarch: %s\n", runtime.GOARCH)
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if b.importPath != "" {
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fmt.Fprintf(b.w, "pkg: %s\n", b.importPath)
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}
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if cpu := sysinfo.CPU.Name(); cpu != "" {
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fmt.Fprintf(b.w, "cpu: %s\n", cpu)
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}
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})
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if b.context != nil {
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// Running go test --test.bench
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b.context.processBench(b) // Must call doBench.
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} else {
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// Running func Benchmark.
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b.doBench()
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}
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}
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func (b *B) doBench() BenchmarkResult {
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go b.launch()
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<-b.signal
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return b.result
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}
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// launch launches the benchmark function. It gradually increases the number
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// of benchmark iterations until the benchmark runs for the requested benchtime.
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// launch is run by the doBench function as a separate goroutine.
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// run1 must have been called on b.
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func (b *B) launch() {
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// Signal that we're done whether we return normally
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// or by FailNow's runtime.Goexit.
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defer func() {
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b.signal <- true
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}()
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// Run the benchmark for at least the specified amount of time.
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if b.benchTime.n > 0 {
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// We already ran a single iteration in run1.
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// If -benchtime=1x was requested, use that result.
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// See https://golang.org/issue/32051.
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if b.benchTime.n > 1 {
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b.runN(b.benchTime.n)
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}
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} else {
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d := b.benchTime.d
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for n := int64(1); !b.failed && b.duration < d && n < 1e9; {
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last := n
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// Predict required iterations.
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goalns := d.Nanoseconds()
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prevIters := int64(b.N)
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prevns := b.duration.Nanoseconds()
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if prevns <= 0 {
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// Round up, to avoid div by zero.
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prevns = 1
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}
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// Order of operations matters.
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// For very fast benchmarks, prevIters ~= prevns.
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// If you divide first, you get 0 or 1,
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// which can hide an order of magnitude in execution time.
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// So multiply first, then divide.
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n = goalns * prevIters / prevns
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// Run more iterations than we think we'll need (1.2x).
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n += n / 5
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// Don't grow too fast in case we had timing errors previously.
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n = min(n, 100*last)
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// Be sure to run at least one more than last time.
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n = max(n, last+1)
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// Don't run more than 1e9 times. (This also keeps n in int range on 32 bit platforms.)
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n = min(n, 1e9)
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b.runN(int(n))
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}
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}
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b.result = BenchmarkResult{b.N, b.duration, b.bytes, b.netAllocs, b.netBytes, b.extra}
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}
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// ReportMetric adds "n unit" to the reported benchmark results.
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// If the metric is per-iteration, the caller should divide by b.N,
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// and by convention units should end in "/op".
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// ReportMetric overrides any previously reported value for the same unit.
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// ReportMetric panics if unit is the empty string or if unit contains
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// any whitespace.
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// If unit is a unit normally reported by the benchmark framework itself
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// (such as "allocs/op"), ReportMetric will override that metric.
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// Setting "ns/op" to 0 will suppress that built-in metric.
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func (b *B) ReportMetric(n float64, unit string) {
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if unit == "" {
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panic("metric unit must not be empty")
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}
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if strings.IndexFunc(unit, unicode.IsSpace) >= 0 {
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panic("metric unit must not contain whitespace")
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}
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b.extra[unit] = n
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}
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// BenchmarkResult contains the results of a benchmark run.
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type BenchmarkResult struct {
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N int // The number of iterations.
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T time.Duration // The total time taken.
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Bytes int64 // Bytes processed in one iteration.
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MemAllocs uint64 // The total number of memory allocations.
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MemBytes uint64 // The total number of bytes allocated.
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// Extra records additional metrics reported by ReportMetric.
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Extra map[string]float64
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}
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// NsPerOp returns the "ns/op" metric.
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func (r BenchmarkResult) NsPerOp() int64 {
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if v, ok := r.Extra["ns/op"]; ok {
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return int64(v)
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}
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if r.N <= 0 {
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return 0
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}
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return r.T.Nanoseconds() / int64(r.N)
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}
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// mbPerSec returns the "MB/s" metric.
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func (r BenchmarkResult) mbPerSec() float64 {
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if v, ok := r.Extra["MB/s"]; ok {
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return v
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}
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if r.Bytes <= 0 || r.T <= 0 || r.N <= 0 {
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return 0
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}
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return (float64(r.Bytes) * float64(r.N) / 1e6) / r.T.Seconds()
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}
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// AllocsPerOp returns the "allocs/op" metric,
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// which is calculated as r.MemAllocs / r.N.
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func (r BenchmarkResult) AllocsPerOp() int64 {
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if v, ok := r.Extra["allocs/op"]; ok {
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return int64(v)
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}
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if r.N <= 0 {
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return 0
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}
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return int64(r.MemAllocs) / int64(r.N)
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}
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// AllocedBytesPerOp returns the "B/op" metric,
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// which is calculated as r.MemBytes / r.N.
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func (r BenchmarkResult) AllocedBytesPerOp() int64 {
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if v, ok := r.Extra["B/op"]; ok {
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return int64(v)
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}
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if r.N <= 0 {
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return 0
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}
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return int64(r.MemBytes) / int64(r.N)
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}
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// String returns a summary of the benchmark results.
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// It follows the benchmark result line format from
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// https://golang.org/design/14313-benchmark-format, not including the
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// benchmark name.
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// Extra metrics override built-in metrics of the same name.
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// String does not include allocs/op or B/op, since those are reported
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// by MemString.
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func (r BenchmarkResult) String() string {
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buf := new(strings.Builder)
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fmt.Fprintf(buf, "%8d", r.N)
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// Get ns/op as a float.
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ns, ok := r.Extra["ns/op"]
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if !ok {
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ns = float64(r.T.Nanoseconds()) / float64(r.N)
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}
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if ns != 0 {
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buf.WriteByte('\t')
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prettyPrint(buf, ns, "ns/op")
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}
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if mbs := r.mbPerSec(); mbs != 0 {
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fmt.Fprintf(buf, "\t%7.2f MB/s", mbs)
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}
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// Print extra metrics that aren't represented in the standard
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// metrics.
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var extraKeys []string
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for k := range r.Extra {
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switch k {
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case "ns/op", "MB/s", "B/op", "allocs/op":
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// Built-in metrics reported elsewhere.
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continue
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}
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extraKeys = append(extraKeys, k)
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}
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sort.Strings(extraKeys)
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for _, k := range extraKeys {
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buf.WriteByte('\t')
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prettyPrint(buf, r.Extra[k], k)
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}
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return buf.String()
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}
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func prettyPrint(w io.Writer, x float64, unit string) {
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// Print all numbers with 10 places before the decimal point
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// and small numbers with four sig figs. Field widths are
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// chosen to fit the whole part in 10 places while aligning
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// the decimal point of all fractional formats.
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var format string
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switch y := math.Abs(x); {
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case y == 0 || y >= 999.95:
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format = "%10.0f %s"
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case y >= 99.995:
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format = "%12.1f %s"
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case y >= 9.9995:
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format = "%13.2f %s"
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case y >= 0.99995:
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format = "%14.3f %s"
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case y >= 0.099995:
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format = "%15.4f %s"
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case y >= 0.0099995:
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format = "%16.5f %s"
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case y >= 0.00099995:
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format = "%17.6f %s"
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default:
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format = "%18.7f %s"
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}
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fmt.Fprintf(w, format, x, unit)
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}
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// MemString returns r.AllocedBytesPerOp and r.AllocsPerOp in the same format as 'go test'.
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func (r BenchmarkResult) MemString() string {
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return fmt.Sprintf("%8d B/op\t%8d allocs/op",
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r.AllocedBytesPerOp(), r.AllocsPerOp())
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}
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// benchmarkName returns full name of benchmark including procs suffix.
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func benchmarkName(name string, n int) string {
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if n != 1 {
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return fmt.Sprintf("%s-%d", name, n)
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}
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return name
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}
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|
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type benchContext struct {
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match *matcher
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|
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maxLen int // The largest recorded benchmark name.
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extLen int // Maximum extension length.
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}
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|
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// RunBenchmarks is an internal function but exported because it is cross-package;
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// it is part of the implementation of the "go test" command.
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func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) {
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runBenchmarks("", matchString, benchmarks)
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}
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func runBenchmarks(importPath string, matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) bool {
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// If no flag was specified, don't run benchmarks.
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if len(*matchBenchmarks) == 0 {
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return true
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}
|
|
// Collect matching benchmarks and determine longest name.
|
|
maxprocs := 1
|
|
for _, procs := range cpuList {
|
|
if procs > maxprocs {
|
|
maxprocs = procs
|
|
}
|
|
}
|
|
ctx := &benchContext{
|
|
match: newMatcher(matchString, *matchBenchmarks, "-test.bench"),
|
|
extLen: len(benchmarkName("", maxprocs)),
|
|
}
|
|
var bs []InternalBenchmark
|
|
for _, Benchmark := range benchmarks {
|
|
if _, matched, _ := ctx.match.fullName(nil, Benchmark.Name); matched {
|
|
bs = append(bs, Benchmark)
|
|
benchName := benchmarkName(Benchmark.Name, maxprocs)
|
|
if l := len(benchName) + ctx.extLen + 1; l > ctx.maxLen {
|
|
ctx.maxLen = l
|
|
}
|
|
}
|
|
}
|
|
main := &B{
|
|
common: common{
|
|
name: "Main",
|
|
w: os.Stdout,
|
|
bench: true,
|
|
},
|
|
importPath: importPath,
|
|
benchFunc: func(b *B) {
|
|
for _, Benchmark := range bs {
|
|
b.Run(Benchmark.Name, Benchmark.F)
|
|
}
|
|
},
|
|
benchTime: benchTime,
|
|
context: ctx,
|
|
}
|
|
if Verbose() {
|
|
main.chatty = newChattyPrinter(main.w)
|
|
}
|
|
main.runN(1)
|
|
return !main.failed
|
|
}
|
|
|
|
// processBench runs bench b for the configured CPU counts and prints the results.
|
|
func (ctx *benchContext) processBench(b *B) {
|
|
for i, procs := range cpuList {
|
|
for j := uint(0); j < *count; j++ {
|
|
runtime.GOMAXPROCS(procs)
|
|
benchName := benchmarkName(b.name, procs)
|
|
|
|
// If it's chatty, we've already printed this information.
|
|
if b.chatty == nil {
|
|
fmt.Fprintf(b.w, "%-*s\t", ctx.maxLen, benchName)
|
|
}
|
|
// Recompute the running time for all but the first iteration.
|
|
if i > 0 || j > 0 {
|
|
b = &B{
|
|
common: common{
|
|
signal: make(chan bool),
|
|
name: b.name,
|
|
w: b.w,
|
|
chatty: b.chatty,
|
|
bench: true,
|
|
},
|
|
benchFunc: b.benchFunc,
|
|
benchTime: b.benchTime,
|
|
}
|
|
b.run1()
|
|
}
|
|
r := b.doBench()
|
|
if b.failed {
|
|
// The output could be very long here, but probably isn't.
|
|
// We print it all, regardless, because we don't want to trim the reason
|
|
// the benchmark failed.
|
|
fmt.Fprintf(b.w, "--- FAIL: %s\n%s", benchName, b.output)
|
|
continue
|
|
}
|
|
results := r.String()
|
|
if b.chatty != nil {
|
|
fmt.Fprintf(b.w, "%-*s\t", ctx.maxLen, benchName)
|
|
}
|
|
if *benchmarkMemory || b.showAllocResult {
|
|
results += "\t" + r.MemString()
|
|
}
|
|
fmt.Fprintln(b.w, results)
|
|
// Unlike with tests, we ignore the -chatty flag and always print output for
|
|
// benchmarks since the output generation time will skew the results.
|
|
if len(b.output) > 0 {
|
|
b.trimOutput()
|
|
fmt.Fprintf(b.w, "--- BENCH: %s\n%s", benchName, b.output)
|
|
}
|
|
if p := runtime.GOMAXPROCS(-1); p != procs {
|
|
fmt.Fprintf(os.Stderr, "testing: %s left GOMAXPROCS set to %d\n", benchName, p)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Run benchmarks f as a subbenchmark with the given name. It reports
|
|
// whether there were any failures.
|
|
//
|
|
// A subbenchmark is like any other benchmark. A benchmark that calls Run at
|
|
// least once will not be measured itself and will be called once with N=1.
|
|
func (b *B) Run(name string, f func(b *B)) bool {
|
|
// Since b has subbenchmarks, we will no longer run it as a benchmark itself.
|
|
// Release the lock and acquire it on exit to ensure locks stay paired.
|
|
atomic.StoreInt32(&b.hasSub, 1)
|
|
benchmarkLock.Unlock()
|
|
defer benchmarkLock.Lock()
|
|
|
|
benchName, ok, partial := b.name, true, false
|
|
if b.context != nil {
|
|
benchName, ok, partial = b.context.match.fullName(&b.common, name)
|
|
}
|
|
if !ok {
|
|
return true
|
|
}
|
|
var pc [maxStackLen]uintptr
|
|
n := runtime.Callers(2, pc[:])
|
|
sub := &B{
|
|
common: common{
|
|
signal: make(chan bool),
|
|
name: benchName,
|
|
parent: &b.common,
|
|
level: b.level + 1,
|
|
creator: pc[:n],
|
|
w: b.w,
|
|
chatty: b.chatty,
|
|
bench: true,
|
|
},
|
|
importPath: b.importPath,
|
|
benchFunc: f,
|
|
benchTime: b.benchTime,
|
|
context: b.context,
|
|
}
|
|
if partial {
|
|
// Partial name match, like -bench=X/Y matching BenchmarkX.
|
|
// Only process sub-benchmarks, if any.
|
|
atomic.StoreInt32(&sub.hasSub, 1)
|
|
}
|
|
|
|
if b.chatty != nil {
|
|
labelsOnce.Do(func() {
|
|
fmt.Printf("goos: %s\n", runtime.GOOS)
|
|
fmt.Printf("goarch: %s\n", runtime.GOARCH)
|
|
if b.importPath != "" {
|
|
fmt.Printf("pkg: %s\n", b.importPath)
|
|
}
|
|
if cpu := sysinfo.CPU.Name(); cpu != "" {
|
|
fmt.Printf("cpu: %s\n", cpu)
|
|
}
|
|
})
|
|
|
|
fmt.Println(benchName)
|
|
}
|
|
|
|
if sub.run1() {
|
|
sub.run()
|
|
}
|
|
b.add(sub.result)
|
|
return !sub.failed
|
|
}
|
|
|
|
// add simulates running benchmarks in sequence in a single iteration. It is
|
|
// used to give some meaningful results in case func Benchmark is used in
|
|
// combination with Run.
|
|
func (b *B) add(other BenchmarkResult) {
|
|
r := &b.result
|
|
// The aggregated BenchmarkResults resemble running all subbenchmarks as
|
|
// in sequence in a single benchmark.
|
|
r.N = 1
|
|
r.T += time.Duration(other.NsPerOp())
|
|
if other.Bytes == 0 {
|
|
// Summing Bytes is meaningless in aggregate if not all subbenchmarks
|
|
// set it.
|
|
b.missingBytes = true
|
|
r.Bytes = 0
|
|
}
|
|
if !b.missingBytes {
|
|
r.Bytes += other.Bytes
|
|
}
|
|
r.MemAllocs += uint64(other.AllocsPerOp())
|
|
r.MemBytes += uint64(other.AllocedBytesPerOp())
|
|
}
|
|
|
|
// trimOutput shortens the output from a benchmark, which can be very long.
|
|
func (b *B) trimOutput() {
|
|
// The output is likely to appear multiple times because the benchmark
|
|
// is run multiple times, but at least it will be seen. This is not a big deal
|
|
// because benchmarks rarely print, but just in case, we trim it if it's too long.
|
|
const maxNewlines = 10
|
|
for nlCount, j := 0, 0; j < len(b.output); j++ {
|
|
if b.output[j] == '\n' {
|
|
nlCount++
|
|
if nlCount >= maxNewlines {
|
|
b.output = append(b.output[:j], "\n\t... [output truncated]\n"...)
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// A PB is used by RunParallel for running parallel benchmarks.
|
|
type PB struct {
|
|
globalN *uint64 // shared between all worker goroutines iteration counter
|
|
grain uint64 // acquire that many iterations from globalN at once
|
|
cache uint64 // local cache of acquired iterations
|
|
bN uint64 // total number of iterations to execute (b.N)
|
|
}
|
|
|
|
// Next reports whether there are more iterations to execute.
|
|
func (pb *PB) Next() bool {
|
|
if pb.cache == 0 {
|
|
n := atomic.AddUint64(pb.globalN, pb.grain)
|
|
if n <= pb.bN {
|
|
pb.cache = pb.grain
|
|
} else if n < pb.bN+pb.grain {
|
|
pb.cache = pb.bN + pb.grain - n
|
|
} else {
|
|
return false
|
|
}
|
|
}
|
|
pb.cache--
|
|
return true
|
|
}
|
|
|
|
// RunParallel runs a benchmark in parallel.
|
|
// It creates multiple goroutines and distributes b.N iterations among them.
|
|
// The number of goroutines defaults to GOMAXPROCS. To increase parallelism for
|
|
// non-CPU-bound benchmarks, call SetParallelism before RunParallel.
|
|
// RunParallel is usually used with the go test -cpu flag.
|
|
//
|
|
// The body function will be run in each goroutine. It should set up any
|
|
// goroutine-local state and then iterate until pb.Next returns false.
|
|
// It should not use the StartTimer, StopTimer, or ResetTimer functions,
|
|
// because they have global effect. It should also not call Run.
|
|
func (b *B) RunParallel(body func(*PB)) {
|
|
if b.N == 0 {
|
|
return // Nothing to do when probing.
|
|
}
|
|
// Calculate grain size as number of iterations that take ~100µs.
|
|
// 100µs is enough to amortize the overhead and provide sufficient
|
|
// dynamic load balancing.
|
|
grain := uint64(0)
|
|
if b.previousN > 0 && b.previousDuration > 0 {
|
|
grain = 1e5 * uint64(b.previousN) / uint64(b.previousDuration)
|
|
}
|
|
if grain < 1 {
|
|
grain = 1
|
|
}
|
|
// We expect the inner loop and function call to take at least 10ns,
|
|
// so do not do more than 100µs/10ns=1e4 iterations.
|
|
if grain > 1e4 {
|
|
grain = 1e4
|
|
}
|
|
|
|
n := uint64(0)
|
|
numProcs := b.parallelism * runtime.GOMAXPROCS(0)
|
|
var wg sync.WaitGroup
|
|
wg.Add(numProcs)
|
|
for p := 0; p < numProcs; p++ {
|
|
go func() {
|
|
defer wg.Done()
|
|
pb := &PB{
|
|
globalN: &n,
|
|
grain: grain,
|
|
bN: uint64(b.N),
|
|
}
|
|
body(pb)
|
|
}()
|
|
}
|
|
wg.Wait()
|
|
if n <= uint64(b.N) && !b.Failed() {
|
|
b.Fatal("RunParallel: body exited without pb.Next() == false")
|
|
}
|
|
}
|
|
|
|
// SetParallelism sets the number of goroutines used by RunParallel to p*GOMAXPROCS.
|
|
// There is usually no need to call SetParallelism for CPU-bound benchmarks.
|
|
// If p is less than 1, this call will have no effect.
|
|
func (b *B) SetParallelism(p int) {
|
|
if p >= 1 {
|
|
b.parallelism = p
|
|
}
|
|
}
|
|
|
|
// Benchmark benchmarks a single function. It is useful for creating
|
|
// custom benchmarks that do not use the "go test" command.
|
|
//
|
|
// If f depends on testing flags, then Init must be used to register
|
|
// those flags before calling Benchmark and before calling flag.Parse.
|
|
//
|
|
// If f calls Run, the result will be an estimate of running all its
|
|
// subbenchmarks that don't call Run in sequence in a single benchmark.
|
|
func Benchmark(f func(b *B)) BenchmarkResult {
|
|
b := &B{
|
|
common: common{
|
|
signal: make(chan bool),
|
|
w: discard{},
|
|
},
|
|
benchFunc: f,
|
|
benchTime: benchTime,
|
|
}
|
|
if b.run1() {
|
|
b.run()
|
|
}
|
|
return b.result
|
|
}
|
|
|
|
type discard struct{}
|
|
|
|
func (discard) Write(b []byte) (n int, err error) { return len(b), nil }
|