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 main 6 7 // Run a slow C function saving a CPU profile. 8 9 /* 10 #include <stdint.h> 11 12 int salt1; 13 int salt2; 14 15 void cpuHog() { 16 int foo = salt1; 17 int i; 18 19 for (i = 0; i < 100000; i++) { 20 if (foo > 0) { 21 foo *= foo; 22 } else { 23 foo *= foo + 1; 24 } 25 } 26 salt2 = foo; 27 } 28 29 static int cpuHogCount; 30 31 struct cgoTracebackArg { 32 uintptr_t context; 33 uintptr_t sigContext; 34 uintptr_t* buf; 35 uintptr_t max; 36 }; 37 38 // pprofCgoTraceback is passed to runtime.SetCgoTraceback. 39 // For testing purposes it pretends that all CPU hits in C code are in cpuHog. 40 void pprofCgoTraceback(void* parg) { 41 struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg); 42 arg->buf[0] = (uintptr_t)(cpuHog) + 0x10; 43 arg->buf[1] = 0; 44 ++cpuHogCount; 45 } 46 47 // getCpuHogCount fetches the number of times we've seen cpuHog in the 48 // traceback. 49 int getCpuHogCount() { 50 return cpuHogCount; 51 } 52 */ 53 import "C" 54 55 import ( 56 "fmt" 57 "io/ioutil" 58 "os" 59 "runtime" 60 "runtime/pprof" 61 "time" 62 "unsafe" 63 ) 64 65 func init() { 66 register("CgoPprof", CgoPprof) 67 } 68 69 func CgoPprof() { 70 runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoTraceback), nil, nil) 71 72 f, err := ioutil.TempFile("", "prof") 73 if err != nil { 74 fmt.Fprintln(os.Stderr, err) 75 os.Exit(2) 76 } 77 78 if err := pprof.StartCPUProfile(f); err != nil { 79 fmt.Fprintln(os.Stderr, err) 80 os.Exit(2) 81 } 82 83 t0 := time.Now() 84 for C.getCpuHogCount() < 2 && time.Since(t0) < time.Second { 85 C.cpuHog() 86 } 87 88 pprof.StopCPUProfile() 89 90 name := f.Name() 91 if err := f.Close(); err != nil { 92 fmt.Fprintln(os.Stderr, err) 93 os.Exit(2) 94 } 95 96 fmt.Println(name) 97 } 98
