| // Copyright 2009 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. |
| |
| package testing |
| |
| import ( |
| "flag" |
| "fmt" |
| "internal/race" |
| "io" |
| "math" |
| "os" |
| "runtime" |
| "sort" |
| "strconv" |
| "strings" |
| "sync" |
| "sync/atomic" |
| "time" |
| "unicode" |
| ) |
| |
| func initBenchmarkFlags() { |
| matchBenchmarks = flag.String("test.bench", "", "run only benchmarks matching `regexp`") |
| benchmarkMemory = flag.Bool("test.benchmem", false, "print memory allocations for benchmarks") |
| flag.Var(&benchTime, "test.benchtime", "run each benchmark for duration `d`") |
| } |
| |
| var ( |
| matchBenchmarks *string |
| benchmarkMemory *bool |
| |
| benchTime = benchTimeFlag{d: 1 * time.Second} // changed during test of testing package |
| ) |
| |
| type benchTimeFlag struct { |
| d time.Duration |
| n int |
| } |
| |
| func (f *benchTimeFlag) String() string { |
| if f.n > 0 { |
| return fmt.Sprintf("%dx", f.n) |
| } |
| return time.Duration(f.d).String() |
| } |
| |
| func (f *benchTimeFlag) Set(s string) error { |
| if strings.HasSuffix(s, "x") { |
| n, err := strconv.ParseInt(s[:len(s)-1], 10, 0) |
| if err != nil || n <= 0 { |
| return fmt.Errorf("invalid count") |
| } |
| *f = benchTimeFlag{n: int(n)} |
| return nil |
| } |
| d, err := time.ParseDuration(s) |
| if err != nil || d <= 0 { |
| return fmt.Errorf("invalid duration") |
| } |
| *f = benchTimeFlag{d: d} |
| return nil |
| } |
| |
| // Global lock to ensure only one benchmark runs at a time. |
| var benchmarkLock sync.Mutex |
| |
| // Used for every benchmark for measuring memory. |
| var memStats runtime.MemStats |
| |
| // InternalBenchmark is an internal type but exported because it is cross-package; |
| // it is part of the implementation of the "go test" command. |
| type InternalBenchmark struct { |
| Name string |
| F func(b *B) |
| } |
| |
| // B is a type passed to Benchmark functions to manage benchmark |
| // timing and to specify the number of iterations to run. |
| // |
| // A benchmark ends when its Benchmark function returns or calls any of the methods |
| // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods must be called |
| // only from the goroutine running the Benchmark function. |
| // The other reporting methods, such as the variations of Log and Error, |
| // may be called simultaneously from multiple goroutines. |
| // |
| // Like in tests, benchmark logs are accumulated during execution |
| // and dumped to standard output when done. Unlike in tests, benchmark logs |
| // are always printed, so as not to hide output whose existence may be |
| // affecting benchmark results. |
| type B struct { |
| common |
| importPath string // import path of the package containing the benchmark |
| context *benchContext |
| N int |
| previousN int // number of iterations in the previous run |
| previousDuration time.Duration // total duration of the previous run |
| benchFunc func(b *B) |
| benchTime benchTimeFlag |
| bytes int64 |
| missingBytes bool // one of the subbenchmarks does not have bytes set. |
| timerOn bool |
| showAllocResult bool |
| result BenchmarkResult |
| parallelism int // RunParallel creates parallelism*GOMAXPROCS goroutines |
| // The initial states of memStats.Mallocs and memStats.TotalAlloc. |
| startAllocs uint64 |
| startBytes uint64 |
| // The net total of this test after being run. |
| netAllocs uint64 |
| netBytes uint64 |
| // Extra metrics collected by ReportMetric. |
| extra map[string]float64 |
| } |
| |
| // StartTimer starts timing a test. This function is called automatically |
| // before a benchmark starts, but it can also be used to resume timing after |
| // a call to StopTimer. |
| func (b *B) StartTimer() { |
| if !b.timerOn { |
| runtime.ReadMemStats(&memStats) |
| b.startAllocs = memStats.Mallocs |
| b.startBytes = memStats.TotalAlloc |
| b.start = time.Now() |
| b.timerOn = true |
| } |
| } |
| |
| // StopTimer stops timing a test. This can be used to pause the timer |
| // while performing complex initialization that you don't |
| // want to measure. |
| func (b *B) StopTimer() { |
| if b.timerOn { |
| b.duration += time.Since(b.start) |
| runtime.ReadMemStats(&memStats) |
| b.netAllocs += memStats.Mallocs - b.startAllocs |
| b.netBytes += memStats.TotalAlloc - b.startBytes |
| b.timerOn = false |
| } |
| } |
| |
| // ResetTimer zeroes the elapsed benchmark time and memory allocation counters |
| // and deletes user-reported metrics. |
| // It does not affect whether the timer is running. |
| func (b *B) ResetTimer() { |
| if b.extra == nil { |
| // Allocate the extra map before reading memory stats. |
| // Pre-size it to make more allocation unlikely. |
| b.extra = make(map[string]float64, 16) |
| } else { |
| for k := range b.extra { |
| delete(b.extra, k) |
| } |
| } |
| if b.timerOn { |
| runtime.ReadMemStats(&memStats) |
| b.startAllocs = memStats.Mallocs |
| b.startBytes = memStats.TotalAlloc |
| b.start = time.Now() |
| } |
| b.duration = 0 |
| b.netAllocs = 0 |
| b.netBytes = 0 |
| } |
| |
| // SetBytes records the number of bytes processed in a single operation. |
| // If this is called, the benchmark will report ns/op and MB/s. |
| func (b *B) SetBytes(n int64) { b.bytes = n } |
| |
| // ReportAllocs enables malloc statistics for this benchmark. |
| // It is equivalent to setting -test.benchmem, but it only affects the |
| // benchmark function that calls ReportAllocs. |
| func (b *B) ReportAllocs() { |
| b.showAllocResult = true |
| } |
| |
| // runN runs a single benchmark for the specified number of iterations. |
| func (b *B) runN(n int) { |
| benchmarkLock.Lock() |
| defer benchmarkLock.Unlock() |
| defer b.runCleanup(normalPanic) |
| // Try to get a comparable environment for each run |
| // by clearing garbage from previous runs. |
| runtime.GC() |
| b.raceErrors = -race.Errors() |
| b.N = n |
| b.parallelism = 1 |
| b.ResetTimer() |
| b.StartTimer() |
| b.benchFunc(b) |
| b.StopTimer() |
| b.previousN = n |
| b.previousDuration = b.duration |
| b.raceErrors += race.Errors() |
| if b.raceErrors > 0 { |
| b.Errorf("race detected during execution of benchmark") |
| } |
| } |
| |
| func min(x, y int64) int64 { |
| if x > y { |
| return y |
| } |
| return x |
| } |
| |
| func max(x, y int64) int64 { |
| if x < y { |
| return y |
| } |
| return x |
| } |
| |
| // run1 runs the first iteration of benchFunc. It reports whether more |
| // iterations of this benchmarks should be run. |
| func (b *B) run1() bool { |
| if ctx := b.context; ctx != nil { |
| // Extend maxLen, if needed. |
| if n := len(b.name) + ctx.extLen + 1; n > ctx.maxLen { |
| ctx.maxLen = n + 8 // Add additional slack to avoid too many jumps in size. |
| } |
| } |
| go func() { |
| // Signal that we're done whether we return normally |
| // or by FailNow's runtime.Goexit. |
| defer func() { |
| b.signal <- true |
| }() |
| |
| b.runN(1) |
| }() |
| <-b.signal |
| if b.failed { |
| fmt.Fprintf(b.w, "--- FAIL: %s\n%s", b.name, b.output) |
| return false |
| } |
| // Only print the output if we know we are not going to proceed. |
| // Otherwise it is printed in processBench. |
| if atomic.LoadInt32(&b.hasSub) != 0 || b.finished { |
| tag := "BENCH" |
| if b.skipped { |
| tag = "SKIP" |
| } |
| if b.chatty != nil && (len(b.output) > 0 || b.finished) { |
| b.trimOutput() |
| fmt.Fprintf(b.w, "--- %s: %s\n%s", tag, b.name, b.output) |
| } |
| return false |
| } |
| return true |
| } |
| |
| var labelsOnce sync.Once |
| |
| // run executes the benchmark in a separate goroutine, including all of its |
| // subbenchmarks. b must not have subbenchmarks. |
| func (b *B) run() { |
| labelsOnce.Do(func() { |
| fmt.Fprintf(b.w, "goos: %s\n", runtime.GOOS) |
| fmt.Fprintf(b.w, "goarch: %s\n", runtime.GOARCH) |
| if b.importPath != "" { |
| fmt.Fprintf(b.w, "pkg: %s\n", b.importPath) |
| } |
| }) |
| if b.context != nil { |
| // Running go test --test.bench |
| b.context.processBench(b) // Must call doBench. |
| } else { |
| // Running func Benchmark. |
| b.doBench() |
| } |
| } |
| |
| func (b *B) doBench() BenchmarkResult { |
| go b.launch() |
| <-b.signal |
| return b.result |
| } |
| |
| // launch launches the benchmark function. It gradually increases the number |
| // of benchmark iterations until the benchmark runs for the requested benchtime. |
| // launch is run by the doBench function as a separate goroutine. |
| // run1 must have been called on b. |
| func (b *B) launch() { |
| // Signal that we're done whether we return normally |
| // or by FailNow's runtime.Goexit. |
| defer func() { |
| b.signal <- true |
| }() |
| |
| // Run the benchmark for at least the specified amount of time. |
| if b.benchTime.n > 0 { |
| b.runN(b.benchTime.n) |
| } else { |
| d := b.benchTime.d |
| for n := int64(1); !b.failed && b.duration < d && n < 1e9; { |
| last := n |
| // Predict required iterations. |
| goalns := d.Nanoseconds() |
| prevIters := int64(b.N) |
| prevns := b.duration.Nanoseconds() |
| if prevns <= 0 { |
| // Round up, to avoid div by zero. |
| prevns = 1 |
| } |
| // Order of operations matters. |
| // For very fast benchmarks, prevIters ~= prevns. |
| // If you divide first, you get 0 or 1, |
| // which can hide an order of magnitude in execution time. |
| // So multiply first, then divide. |
| n = goalns * prevIters / prevns |
| // Run more iterations than we think we'll need (1.2x). |
| n += n / 5 |
| // Don't grow too fast in case we had timing errors previously. |
| n = min(n, 100*last) |
| // Be sure to run at least one more than last time. |
| n = max(n, last+1) |
| // Don't run more than 1e9 times. (This also keeps n in int range on 32 bit platforms.) |
| n = min(n, 1e9) |
| b.runN(int(n)) |
| } |
| } |
| b.result = BenchmarkResult{b.N, b.duration, b.bytes, b.netAllocs, b.netBytes, b.extra} |
| } |
| |
| // ReportMetric adds "n unit" to the reported benchmark results. |
| // If the metric is per-iteration, the caller should divide by b.N, |
| // and by convention units should end in "/op". |
| // ReportMetric overrides any previously reported value for the same unit. |
| // ReportMetric panics if unit is the empty string or if unit contains |
| // any whitespace. |
| // If unit is a unit normally reported by the benchmark framework itself |
| // (such as "allocs/op"), ReportMetric will override that metric. |
| // Setting "ns/op" to 0 will suppress that built-in metric. |
| func (b *B) ReportMetric(n float64, unit string) { |
| if unit == "" { |
| panic("metric unit must not be empty") |
| } |
| if strings.IndexFunc(unit, unicode.IsSpace) >= 0 { |
| panic("metric unit must not contain whitespace") |
| } |
| b.extra[unit] = n |
| } |
| |
| // BenchmarkResult contains the results of a benchmark run. |
| type BenchmarkResult struct { |
| N int // The number of iterations. |
| T time.Duration // The total time taken. |
| Bytes int64 // Bytes processed in one iteration. |
| MemAllocs uint64 // The total number of memory allocations. |
| MemBytes uint64 // The total number of bytes allocated. |
| |
| // Extra records additional metrics reported by ReportMetric. |
| Extra map[string]float64 |
| } |
| |
| // NsPerOp returns the "ns/op" metric. |
| func (r BenchmarkResult) NsPerOp() int64 { |
| if v, ok := r.Extra["ns/op"]; ok { |
| return int64(v) |
| } |
| if r.N <= 0 { |
| return 0 |
| } |
| return r.T.Nanoseconds() / int64(r.N) |
| } |
| |
| // mbPerSec returns the "MB/s" metric. |
| func (r BenchmarkResult) mbPerSec() float64 { |
| if v, ok := r.Extra["MB/s"]; ok { |
| return v |
| } |
| if r.Bytes <= 0 || r.T <= 0 || r.N <= 0 { |
| return 0 |
| } |
| return (float64(r.Bytes) * float64(r.N) / 1e6) / r.T.Seconds() |
| } |
| |
| // AllocsPerOp returns the "allocs/op" metric, |
| // which is calculated as r.MemAllocs / r.N. |
| func (r BenchmarkResult) AllocsPerOp() int64 { |
| if v, ok := r.Extra["allocs/op"]; ok { |
| return int64(v) |
| } |
| if r.N <= 0 { |
| return 0 |
| } |
| return int64(r.MemAllocs) / int64(r.N) |
| } |
| |
| // AllocedBytesPerOp returns the "B/op" metric, |
| // which is calculated as r.MemBytes / r.N. |
| func (r BenchmarkResult) AllocedBytesPerOp() int64 { |
| if v, ok := r.Extra["B/op"]; ok { |
| return int64(v) |
| } |
| if r.N <= 0 { |
| return 0 |
| } |
| return int64(r.MemBytes) / int64(r.N) |
| } |
| |
| // String returns a summary of the benchmark results. |
| // It follows the benchmark result line format from |
| // https://golang.org/design/14313-benchmark-format, not including the |
| // benchmark name. |
| // Extra metrics override built-in metrics of the same name. |
| // String does not include allocs/op or B/op, since those are reported |
| // by MemString. |
| func (r BenchmarkResult) String() string { |
| buf := new(strings.Builder) |
| fmt.Fprintf(buf, "%8d", r.N) |
| |
| // Get ns/op as a float. |
| ns, ok := r.Extra["ns/op"] |
| if !ok { |
| ns = float64(r.T.Nanoseconds()) / float64(r.N) |
| } |
| if ns != 0 { |
| buf.WriteByte('\t') |
| prettyPrint(buf, ns, "ns/op") |
| } |
| |
| if mbs := r.mbPerSec(); mbs != 0 { |
| fmt.Fprintf(buf, "\t%7.2f MB/s", mbs) |
| } |
| |
| // Print extra metrics that aren't represented in the standard |
| // metrics. |
| var extraKeys []string |
| for k := range r.Extra { |
| switch k { |
| case "ns/op", "MB/s", "B/op", "allocs/op": |
| // Built-in metrics reported elsewhere. |
| continue |
| } |
| extraKeys = append(extraKeys, k) |
| } |
| sort.Strings(extraKeys) |
| for _, k := range extraKeys { |
| buf.WriteByte('\t') |
| prettyPrint(buf, r.Extra[k], k) |
| } |
| return buf.String() |
| } |
| |
| func prettyPrint(w io.Writer, x float64, unit string) { |
| // Print all numbers with 10 places before the decimal point |
| // and small numbers with three sig figs. |
| var format string |
| switch y := math.Abs(x); { |
| case y == 0 || y >= 99.95: |
| format = "%10.0f %s" |
| case y >= 9.995: |
| format = "%12.1f %s" |
| case y >= 0.9995: |
| format = "%13.2f %s" |
| case y >= 0.09995: |
| format = "%14.3f %s" |
| case y >= 0.009995: |
| format = "%15.4f %s" |
| case y >= 0.0009995: |
| format = "%16.5f %s" |
| default: |
| format = "%17.6f %s" |
| } |
| fmt.Fprintf(w, format, x, unit) |
| } |
| |
| // MemString returns r.AllocedBytesPerOp and r.AllocsPerOp in the same format as 'go test'. |
| func (r BenchmarkResult) MemString() string { |
| return fmt.Sprintf("%8d B/op\t%8d allocs/op", |
| r.AllocedBytesPerOp(), r.AllocsPerOp()) |
| } |
| |
| // benchmarkName returns full name of benchmark including procs suffix. |
| func benchmarkName(name string, n int) string { |
| if n != 1 { |
| return fmt.Sprintf("%s-%d", name, n) |
| } |
| return name |
| } |
| |
| type benchContext struct { |
| match *matcher |
| |
| maxLen int // The largest recorded benchmark name. |
| extLen int // Maximum extension length. |
| } |
| |
| // RunBenchmarks is an internal function but exported because it is cross-package; |
| // it is part of the implementation of the "go test" command. |
| func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) { |
| runBenchmarks("", matchString, benchmarks) |
| } |
| |
| func runBenchmarks(importPath string, matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) bool { |
| // If no flag was specified, don't run benchmarks. |
| if len(*matchBenchmarks) == 0 { |
| return true |
| } |
| // 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) |
| } |
| }) |
| |
| 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 } |