github.com/4ad/go@v0.0.0-20161219182952-69a12818b605/src/runtime/testdata/testprogcgo/threadpprof.go (about)

     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  // +build !plan9,!windows
     6  
     7  package main
     8  
     9  // Run a slow C function saving a CPU profile.
    10  
    11  /*
    12  #include <stdint.h>
    13  #include <time.h>
    14  #include <pthread.h>
    15  
    16  int threadSalt1;
    17  int threadSalt2;
    18  
    19  void cpuHogThread() {
    20  	int foo = threadSalt1;
    21  	int i;
    22  
    23  	for (i = 0; i < 100000; i++) {
    24  		if (foo > 0) {
    25  			foo *= foo;
    26  		} else {
    27  			foo *= foo + 1;
    28  		}
    29  	}
    30  	threadSalt2 = foo;
    31  }
    32  
    33  static int cpuHogThreadCount;
    34  
    35  struct cgoTracebackArg {
    36  	uintptr_t  context;
    37  	uintptr_t  sigContext;
    38  	uintptr_t* buf;
    39  	uintptr_t  max;
    40  };
    41  
    42  static void *pprofThread(void* p) {
    43  	time_t start;
    44  
    45  	(void)p;
    46  	start = time(NULL);
    47  	while (__sync_add_and_fetch(&cpuHogThreadCount, 0) < 2 && time(NULL) - start < 2) {
    48  		cpuHogThread();
    49  	}
    50  }
    51  
    52  
    53  // pprofCgoThreadTraceback is passed to runtime.SetCgoTraceback.
    54  // For testing purposes it pretends that all CPU hits in C code are in cpuHog.
    55  void pprofCgoThreadTraceback(void* parg) {
    56  	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
    57  	arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
    58  	arg->buf[1] = 0;
    59  	__sync_add_and_fetch(&cpuHogThreadCount, 1);
    60  }
    61  
    62  // getCPUHogThreadCount fetches the number of times we've seen cpuHogThread
    63  // in the traceback.
    64  int getCPUHogThreadCount() {
    65  	return __sync_add_and_fetch(&cpuHogThreadCount, 0);
    66  }
    67  */
    68  import "C"
    69  
    70  import (
    71  	"fmt"
    72  	"io/ioutil"
    73  	"os"
    74  	"runtime"
    75  	"runtime/pprof"
    76  	"time"
    77  	"unsafe"
    78  )
    79  
    80  func init() {
    81  	register("CgoPprofThread", CgoPprofThread)
    82  }
    83  
    84  func CgoPprofThread() {
    85  	runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoThreadTraceback), nil, nil)
    86  
    87  	f, err := ioutil.TempFile("", "prof")
    88  	if err != nil {
    89  		fmt.Fprintln(os.Stderr, err)
    90  		os.Exit(2)
    91  	}
    92  
    93  	if err := pprof.StartCPUProfile(f); err != nil {
    94  		fmt.Fprintln(os.Stderr, err)
    95  		os.Exit(2)
    96  	}
    97  
    98  	t0 := time.Now()
    99  	for C.getCPUHogThreadCount() < 2 && time.Since(t0) < time.Second {
   100  		time.Sleep(100 * time.Millisecond)
   101  	}
   102  
   103  	pprof.StopCPUProfile()
   104  
   105  	name := f.Name()
   106  	if err := f.Close(); err != nil {
   107  		fmt.Fprintln(os.Stderr, err)
   108  		os.Exit(2)
   109  	}
   110  
   111  	fmt.Println(name)
   112  }