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//go:build !plan9 && !windows
6// +build !plan9,!windows
7
8package main
9
10// Run a slow C function saving a CPU profile.
11
12/*
13#include <stdint.h>
14#include <time.h>
15#include <pthread.h>
16
17int threadSalt1;
18int threadSalt2;
19
20static pthread_t tid;
21
22void cpuHogThread() {
23	int foo = threadSalt1;
24	int i;
25
26	for (i = 0; i < 100000; i++) {
27		if (foo > 0) {
28			foo *= foo;
29		} else {
30			foo *= foo + 1;
31		}
32	}
33	threadSalt2 = foo;
34}
35
36void cpuHogThread2() {
37}
38
39struct cgoTracebackArg {
40	uintptr_t  context;
41	uintptr_t  sigContext;
42	uintptr_t* buf;
43	uintptr_t  max;
44};
45
46// pprofCgoThreadTraceback is passed to runtime.SetCgoTraceback.
47// For testing purposes it pretends that all CPU hits on the cpuHog
48// C thread are in cpuHog.
49void pprofCgoThreadTraceback(void* parg) {
50	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
51	if (pthread_self() == tid) {
52		arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
53		arg->buf[1] = (uintptr_t)(cpuHogThread2) + 0x4;
54		arg->buf[2] = 0;
55	} else
56		arg->buf[0] = 0;
57}
58
59static void* cpuHogDriver(void* arg __attribute__ ((unused))) {
60	while (1) {
61		cpuHogThread();
62	}
63	return 0;
64}
65
66void runCPUHogThread(void) {
67	pthread_create(&tid, 0, cpuHogDriver, 0);
68}
69*/
70import "C"
71
72import (
73	"context"
74	"fmt"
75	"os"
76	"runtime"
77	"runtime/pprof"
78	"time"
79	"unsafe"
80)
81
82func init() {
83	register("CgoPprofThread", CgoPprofThread)
84	register("CgoPprofThreadNoTraceback", CgoPprofThreadNoTraceback)
85}
86
87func CgoPprofThread() {
88	runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoThreadTraceback), nil, nil)
89	pprofThread()
90}
91
92func CgoPprofThreadNoTraceback() {
93	pprofThread()
94}
95
96func pprofThread() {
97	f, err := os.CreateTemp("", "prof")
98	if err != nil {
99		fmt.Fprintln(os.Stderr, err)
100		os.Exit(2)
101	}
102
103	if err := pprof.StartCPUProfile(f); err != nil {
104		fmt.Fprintln(os.Stderr, err)
105		os.Exit(2)
106	}
107
108	// This goroutine may receive a profiling signal while creating the C-owned
109	// thread. If it does, the SetCgoTraceback handler will make the leaf end of
110	// the stack look almost (but not exactly) like the stacks the test case is
111	// trying to find. Attach a profiler label so the test can filter out those
112	// confusing samples.
113	pprof.Do(context.Background(), pprof.Labels("ignore", "ignore"), func(ctx context.Context) {
114		C.runCPUHogThread()
115	})
116
117	time.Sleep(1 * time.Second)
118
119	pprof.StopCPUProfile()
120
121	name := f.Name()
122	if err := f.Close(); err != nil {
123		fmt.Fprintln(os.Stderr, err)
124		os.Exit(2)
125	}
126
127	fmt.Println(name)
128}
129