blob: cb30ec5b250d67950fb4391d9ab1d00f20010ed7 [file] [log] [blame]
// Copyright 2016 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 main
// Run a slow C function saving a CPU profile.
/*
#include <stdint.h>
int salt1;
int salt2;
void cpuHog() {
int foo = salt1;
int i;
for (i = 0; i < 100000; i++) {
if (foo > 0) {
foo *= foo;
} else {
foo *= foo + 1;
}
}
salt2 = foo;
}
static int cpuHogCount;
struct cgoTracebackArg {
uintptr_t context;
uintptr_t sigContext;
uintptr_t* buf;
uintptr_t max;
};
// pprofCgoTraceback is passed to runtime.SetCgoTraceback.
// For testing purposes it pretends that all CPU hits in C code are in cpuHog.
void pprofCgoTraceback(void* parg) {
struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
arg->buf[0] = (uintptr_t)(cpuHog) + 0x10;
arg->buf[1] = 0;
++cpuHogCount;
}
// getCpuHogCount fetches the number of times we've seen cpuHog in the
// traceback.
int getCpuHogCount() {
return cpuHogCount;
}
*/
import "C"
import (
"fmt"
"io/ioutil"
"os"
"runtime"
"runtime/pprof"
"time"
"unsafe"
)
func init() {
register("CgoPprof", CgoPprof)
}
func CgoPprof() {
runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoTraceback), nil, nil)
f, err := ioutil.TempFile("", "prof")
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
if err := pprof.StartCPUProfile(f); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
t0 := time.Now()
for C.getCpuHogCount() < 2 && time.Since(t0) < time.Second {
C.cpuHog()
}
pprof.StopCPUProfile()
name := f.Name()
if err := f.Close(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
fmt.Println(name)
}