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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.
//go:build !plan9 && !windows
// +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;
static pthread_t tid;
void cpuHogThread() {
int foo = threadSalt1;
int i;
for (i = 0; i < 100000; i++) {
if (foo > 0) {
foo *= foo;
} else {
foo *= foo + 1;
}
}
threadSalt2 = foo;
}
void cpuHogThread2() {
}
struct cgoTracebackArg {
uintptr_t context;
uintptr_t sigContext;
uintptr_t* buf;
uintptr_t max;
};
// pprofCgoThreadTraceback is passed to runtime.SetCgoTraceback.
// For testing purposes it pretends that all CPU hits on the cpuHog
// C thread are in cpuHog.
void pprofCgoThreadTraceback(void* parg) {
struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
if (pthread_self() == tid) {
arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
arg->buf[1] = (uintptr_t)(cpuHogThread2) + 0x4;
arg->buf[2] = 0;
} else
arg->buf[0] = 0;
}
static void* cpuHogDriver(void* arg __attribute__ ((unused))) {
while (1) {
cpuHogThread();
}
return 0;
}
void runCPUHogThread(void) {
pthread_create(&tid, 0, cpuHogDriver, 0);
}
*/
import "C"
import (
"context"
"fmt"
"os"
"runtime"
"runtime/pprof"
"time"
"unsafe"
)
func init() {
register("CgoPprofThread", CgoPprofThread)
register("CgoPprofThreadNoTraceback", CgoPprofThreadNoTraceback)
}
func CgoPprofThread() {
runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoThreadTraceback), nil, nil)
pprofThread()
}
func CgoPprofThreadNoTraceback() {
pprofThread()
}
func pprofThread() {
f, err := os.CreateTemp("", "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)
}
// This goroutine may receive a profiling signal while creating the C-owned
// thread. If it does, the SetCgoTraceback handler will make the leaf end of
// the stack look almost (but not exactly) like the stacks the test case is
// trying to find. Attach a profiler label so the test can filter out those
// confusing samples.
pprof.Do(context.Background(), pprof.Labels("ignore", "ignore"), func(ctx context.Context) {
C.runCPUHogThread()
})
time.Sleep(1 * time.Second)
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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