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// 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.
// +build !plan9,!windows
package main
// Run a slow C function saving a CPU profile.
/*
#include <stdint.h>
#include <time.h>
#include <pthread.h>
int threadSalt1;
int threadSalt2;
void cpuHogThread() {
int foo = threadSalt1;
int i;
for (i = 0; i < 100000; i++) {
if (foo > 0) {
foo *= foo;
} else {
foo *= foo + 1;
}
}
threadSalt2 = foo;
}
static int cpuHogThreadCount;
struct cgoTracebackArg {
uintptr_t context;
uintptr_t sigContext;
uintptr_t* buf;
uintptr_t max;
};
static void *pprofThread(void* p) {
time_t start;
(void)p;
start = time(NULL);
while (__sync_add_and_fetch(&cpuHogThreadCount, 0) < 2 && time(NULL) - start < 2) {
cpuHogThread();
}
}
// pprofCgoThreadTraceback is passed to runtime.SetCgoTraceback.
// For testing purposes it pretends that all CPU hits in C code are in cpuHog.
void pprofCgoThreadTraceback(void* parg) {
struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
arg->buf[1] = 0;
__sync_add_and_fetch(&cpuHogThreadCount, 1);
}
// getCPUHogThreadCount fetches the number of times we've seen cpuHogThread
// in the traceback.
int getCPUHogThreadCount() {
return __sync_add_and_fetch(&cpuHogThreadCount, 0);
}
*/
import "C"
import (
"fmt"
"io/ioutil"
"os"
"runtime"
"runtime/pprof"
"time"
"unsafe"
)
func init() {
register("CgoPprofThread", CgoPprofThread)
}
func CgoPprofThread() {
runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoThreadTraceback), 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.getCPUHogThreadCount() < 2 && time.Since(t0) < time.Second {
time.Sleep(100 * time.Millisecond)
}
pprof.StopCPUProfile()
name := f.Name()
if err := f.Close(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
fmt.Println(name)
}
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