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Source file src/runtime/testdata/testprogcgo/pprof.go

Documentation: runtime/testdata/testprogcgo

     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  

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