mirror of
https://github.com/golang/go
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89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
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// Copyright 2012 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 main
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import (
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"flag"
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"fmt"
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"log"
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"os"
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"runtime"
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"runtime/pprof"
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"unsafe"
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)
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const BranchingFactor = 4
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type Object struct {
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child [BranchingFactor]*Object
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}
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var (
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cpus = flag.Int("cpus", 1, "number of cpus to use")
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heapsize = flag.Int64("heapsize", 100*1024*1024, "size of the heap in bytes")
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cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
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lastPauseNs uint64 = 0
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lastFree uint64 = 0
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heap *Object
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calls [20]int
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numobjects int64
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)
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func buildHeap() {
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objsize := int64(unsafe.Sizeof(Object{}))
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heap, _ = buildTree(float64(objsize), float64(*heapsize), 0)
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fmt.Printf("*** built heap: %.0f MB; (%d objects * %d bytes)\n",
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float64(*heapsize)/1048576, numobjects, objsize)
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}
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func buildTree(objsize, size float64, depth int) (*Object, float64) {
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calls[depth]++
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x := &Object{}
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numobjects++
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subtreeSize := (size - objsize) / BranchingFactor
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alloc := objsize
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for i := 0; i < BranchingFactor && alloc < size; i++ {
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c, n := buildTree(objsize, subtreeSize, depth+1)
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x.child[i] = c
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alloc += n
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}
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return x, alloc
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}
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func gc() {
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runtime.GC()
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runtime.UpdateMemStats()
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pause := runtime.MemStats.PauseTotalNs
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inuse := runtime.MemStats.Alloc
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free := runtime.MemStats.TotalAlloc - inuse
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fmt.Printf("gc pause: %8.3f ms; collect: %8.0f MB; heapsize: %8.0f MB\n",
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float64(pause-lastPauseNs)/1e6,
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float64(free-lastFree)/1048576,
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float64(inuse)/1048576)
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lastPauseNs = pause
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lastFree = free
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}
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func main() {
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flag.Parse()
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buildHeap()
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runtime.GOMAXPROCS(*cpus)
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runtime.UpdateMemStats()
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lastPauseNs = runtime.MemStats.PauseTotalNs
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lastFree = runtime.MemStats.TotalAlloc - runtime.MemStats.Alloc
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if *cpuprofile != "" {
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f, err := os.Create(*cpuprofile)
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if err != nil {
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log.Fatal(err)
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}
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pprof.StartCPUProfile(f)
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defer pprof.StopCPUProfile()
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}
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for i := 0; i < 10; i++ {
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gc()
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}
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}
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