C++11 多线程

发表于 | 分类于

多线程死锁

1、死锁实例: 连环锁

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65

#include <iostream>           
#include <queue>
#include <thread>             
#include <mutex>              
#include <condition_variable> 

std::mutex g_mutex;
std::condition_variable g_produce, g_consume;  

std::queue<int> g_queue;     

static const int maxSize = 100;

static const int consumeSize = 5;
static const int productSize = 10;
void consumer() 
{ 
	while(g_queue.size() <= maxSize )
	{ 
		std::this_thread::sleep_for(std::chrono::milliseconds(1000));

		std::unique_lock<std::mutex> lck(g_mutex);
		
		g_consume.wait(lck);
		std::cout << "@@@-> consumer " << ": ";
		std::cout << std::this_thread::get_id() << "    : ";
	    if(g_queue.size() > 0) g_queue.pop();
	    std::cout << g_queue.size() << '\n';
	    // nodity(wake up) producer 
	    g_produce.notify_all();
	}
}

void producer()
{
    while(g_queue.size() <= maxSize)
    {
    	std::this_thread::sleep_for(std::chrono::milliseconds(1000));

    	std::unique_lock<std::mutex> lck(g_mutex);
    	
    	g_produce.wait_for(lck,std::chrono::seconds(1));
 
    	std::cout << "###-> producer "  << ": ";
    	std::cout << std::this_thread::get_id() << "    : ";
    	g_queue.push(99);
    	std::cout << g_queue.size() << '\n';
    	// notify(wake up) consumer 
	   	g_consume.notify_all(); 
    } 
}

int main(int argc, char const *argv[])
{
	std::vector<std::thread> vcthread;
	for (int i = 0; i < 2; ++i)
	{
		vcthread.emplace_back(producer);
		vcthread.emplace_back(consumer);
	}
	for( auto & th : vcthread)
		th.join();
	return 0;
}

修改如下, 调整锁的作用域

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

#include <iostream>           
#include <queue>
#include <thread>             
#include <mutex>              
#include <condition_variable> 


std::mutex g_mutex;
std::condition_variable g_produce, g_consume;  

std::queue<int> g_queue;     

static const int maxSize = 100;

static const int consumeSize = 5;
static const int productSize = 10;
void consumer() 
{ 
	std::unique_lock<std::mutex> lck(g_mutex);
	while(g_queue.size() <= maxSize )
	{ 
		std::this_thread::sleep_for(std::chrono::milliseconds(1000));

		
		std::cout << "@@@<<<" << "\n";
		g_consume.wait(lck);
		std::cout << "@@@-> consumer " << ": ";
		std::cout << std::this_thread::get_id() << "    : ";
	    if(g_queue.size() > 0) g_queue.pop();
	    std::cout << g_queue.size() << '\n';
	    // nodity(wake up) producer 
	    g_produce.notify_all();
	   

	}
}

void producer()
{
	std::unique_lock<std::mutex> lck(g_mutex);
    while(g_queue.size() <= maxSize)
    {
    	std::this_thread::sleep_for(std::chrono::milliseconds(1000));
    	if(g_queue.size() == 0)
    	{
    		std::cout << "####<<<" << "\n";
    		g_produce.wait_for(lck,std::chrono::seconds(1));
    	}
    	else
    	{
    		std::cout << "####>>>" << "\n";
    		g_produce.wait(lck);
    	}
    	
    	std::cout << "###-> producer "  << ": ";
    	std::cout << std::this_thread::get_id() << "    : ";
    	g_queue.push(99);
    	std::cout << g_queue.size() << '\n';
    	// notify(wake up) consumer 
	   	g_consume.notify_all(); 
	   	

    } 
}

int main(int argc, char const *argv[])
{
	std::vector<std::thread> vcthread;
	
	for (int i = 0; i < 2; ++i)
	{
		vcthread.emplace_back(producer);
		vcthread.emplace_back(consumer);
	}

	for( auto & th : vcthread)
		th.join();
	return 0;
}