1.C语言版

视频教程点我查看

1.1 任务队列

1
2
3
4
5
6
// 任务结构体
typedef struct Task
{
    void (*function)(void* arg);
    void* arg;
}Task;

1.2 线程池定义

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
// 线程池结构体
struct ThreadPool
{
    // 任务队列
    Task* taskQ;
    int queueCapacity;  // 容量
    int queueSize;      // 当前任务个数
    int queueFront;     // 队头 -> 取数据
    int queueRear;      // 队尾 -> 放数据

    pthread_t managerID;    // 管理者线程ID
    pthread_t *threadIDs;   // 工作的线程ID
    int minNum;             // 最小线程数量
    int maxNum;             // 最大线程数量
    int busyNum;            // 忙的线程的个数
    int liveNum;            // 存活的线程的个数
    int exitNum;            // 要销毁的线程个数
    pthread_mutex_t mutexPool;  // 锁整个的线程池
    pthread_mutex_t mutexBusy;  // 锁busyNum变量
    pthread_cond_t notFull;     // 任务队列是不是满了
    pthread_cond_t notEmpty;    // 任务队列是不是空了

    int shutdown;           // 是不是要销毁线程池, 销毁为1, 不销毁为0
};

1.3 头文件声明

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
#ifndef _THREADPOOL_H
#define _THREADPOOL_H

typedef struct ThreadPool ThreadPool;
// 创建线程池并初始化
ThreadPool *threadPoolCreate(int min, int max, int queueSize);

// 销毁线程池
int threadPoolDestroy(ThreadPool* pool);

// 给线程池添加任务
void threadPoolAdd(ThreadPool* pool, void(*func)(void*), void* arg);

// 获取线程池中工作的线程的个数
int threadPoolBusyNum(ThreadPool* pool);

// 获取线程池中活着的线程的个数
int threadPoolAliveNum(ThreadPool* pool);

//////////////////////
// 工作的线程(消费者线程)任务函数
void* worker(void* arg);
// 管理者线程任务函数
void* manager(void* arg);
// 单个线程退出
void threadExit(ThreadPool* pool);
#endif  // _THREADPOOL_H

1.4 源文件定义

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
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
ThreadPool* threadPoolCreate(int min, int max, int queueSize)
{
    ThreadPool* pool = (ThreadPool*)malloc(sizeof(ThreadPool));
    do 
    {
        if (pool == NULL)
        {
            printf("malloc threadpool fail...\n");
            break;
        }

        pool->threadIDs = (pthread_t*)malloc(sizeof(pthread_t) * max);
        if (pool->threadIDs == NULL)
        {
            printf("malloc threadIDs fail...\n");
            break;
        }
        memset(pool->threadIDs, 0, sizeof(pthread_t) * max);
        pool->minNum = min;
        pool->maxNum = max;
        pool->busyNum = 0;
        pool->liveNum = min;    // 和最小个数相等
        pool->exitNum = 0;

        if (pthread_mutex_init(&pool->mutexPool, NULL) != 0 ||
            pthread_mutex_init(&pool->mutexBusy, NULL) != 0 ||
            pthread_cond_init(&pool->notEmpty, NULL) != 0 ||
            pthread_cond_init(&pool->notFull, NULL) != 0)
        {
            printf("mutex or condition init fail...\n");
            break;
        }

        // 任务队列
        pool->taskQ = (Task*)malloc(sizeof(Task) * queueSize);
        pool->queueCapacity = queueSize;
        pool->queueSize = 0;
        pool->queueFront = 0;
        pool->queueRear = 0;

        pool->shutdown = 0;

        // 创建线程
        pthread_create(&pool->managerID, NULL, manager, pool);
        for (int i = 0; i < min; ++i)
        {
            pthread_create(&pool->threadIDs[i], NULL, worker, pool);
        }
        return pool;
    } while (0);

    // 释放资源
    if (pool && pool->threadIDs) free(pool->threadIDs);
    if (pool && pool->taskQ) free(pool->taskQ);
    if (pool) free(pool);

    return NULL;
}

int threadPoolDestroy(ThreadPool* pool)
{
    if (pool == NULL)
    {
        return -1;
    }

    // 关闭线程池
    pool->shutdown = 1;
    // 阻塞回收管理者线程
    pthread_join(pool->managerID, NULL);
    // 唤醒阻塞的消费者线程
    for (int i = 0; i < pool->liveNum; ++i)
    {
        pthread_cond_signal(&pool->notEmpty);
    }
    // 释放堆内存
    if (pool->taskQ)
    {
        free(pool->taskQ);
    }
    if (pool->threadIDs)
    {
        free(pool->threadIDs);
    }

    pthread_mutex_destroy(&pool->mutexPool);
    pthread_mutex_destroy(&pool->mutexBusy);
    pthread_cond_destroy(&pool->notEmpty);
    pthread_cond_destroy(&pool->notFull);

    free(pool);
    pool = NULL;

    return 0;
}


void threadPoolAdd(ThreadPool* pool, void(*func)(void*), void* arg)
{
    pthread_mutex_lock(&pool->mutexPool);
    while (pool->queueSize == pool->queueCapacity && !pool->shutdown)
    {
        // 阻塞生产者线程
        pthread_cond_wait(&pool->notFull, &pool->mutexPool);
    }
    if (pool->shutdown)
    {
        pthread_mutex_unlock(&pool->mutexPool);
        return;
    }
    // 添加任务
    pool->taskQ[pool->queueRear].function = func;
    pool->taskQ[pool->queueRear].arg = arg;
    pool->queueRear = (pool->queueRear + 1) % pool->queueCapacity;
    pool->queueSize++;

    pthread_cond_signal(&pool->notEmpty);
    pthread_mutex_unlock(&pool->mutexPool);
}

int threadPoolBusyNum(ThreadPool* pool)
{
    pthread_mutex_lock(&pool->mutexBusy);
    int busyNum = pool->busyNum;
    pthread_mutex_unlock(&pool->mutexBusy);
    return busyNum;
}

int threadPoolAliveNum(ThreadPool* pool)
{
    pthread_mutex_lock(&pool->mutexPool);
    int aliveNum = pool->liveNum;
    pthread_mutex_unlock(&pool->mutexPool);
    return aliveNum;
}

void* worker(void* arg)
{
    ThreadPool* pool = (ThreadPool*)arg;

    while (1)
    {
        pthread_mutex_lock(&pool->mutexPool);
        // 当前任务队列是否为空
        while (pool->queueSize == 0 && !pool->shutdown)
        {
            // 阻塞工作线程
            pthread_cond_wait(&pool->notEmpty, &pool->mutexPool);

            // 判断是不是要销毁线程
            if (pool->exitNum > 0)
            {
                pool->exitNum--;
                if (pool->liveNum > pool->minNum)
                {
                    pool->liveNum--;
                    pthread_mutex_unlock(&pool->mutexPool);
                    threadExit(pool);
                }
            }
        }

        // 判断线程池是否被关闭了
        if (pool->shutdown)
        {
            pthread_mutex_unlock(&pool->mutexPool);
            threadExit(pool);
        }

        // 从任务队列中取出一个任务
        Task task;
        task.function = pool->taskQ[pool->queueFront].function;
        task.arg = pool->taskQ[pool->queueFront].arg;
        // 移动头结点
        pool->queueFront = (pool->queueFront + 1) % pool->queueCapacity;
        pool->queueSize--;
        // 解锁
        pthread_cond_signal(&pool->notFull);
        pthread_mutex_unlock(&pool->mutexPool);

        printf("thread %ld start working...\n", pthread_self());
        pthread_mutex_lock(&pool->mutexBusy);
        pool->busyNum++;
        pthread_mutex_unlock(&pool->mutexBusy);
        task.function(task.arg);
        free(task.arg);
        task.arg = NULL;

        printf("thread %ld end working...\n", pthread_self());
        pthread_mutex_lock(&pool->mutexBusy);
        pool->busyNum--;
        pthread_mutex_unlock(&pool->mutexBusy);
    }
    return NULL;
}

void* manager(void* arg)
{
    ThreadPool* pool = (ThreadPool*)arg;
    while (!pool->shutdown)
    {
        // 每隔3s检测一次
        sleep(3);

        // 取出线程池中任务的数量和当前线程的数量
        pthread_mutex_lock(&pool->mutexPool);
        int queueSize = pool->queueSize;
        int liveNum = pool->liveNum;
        pthread_mutex_unlock(&pool->mutexPool);

        // 取出忙的线程的数量
        pthread_mutex_lock(&pool->mutexBusy);
        int busyNum = pool->busyNum;
        pthread_mutex_unlock(&pool->mutexBusy);

        // 添加线程
        // 任务的个数>存活的线程个数 && 存活的线程数<最大线程数
        if (queueSize > liveNum && liveNum < pool->maxNum)
        {
            pthread_mutex_lock(&pool->mutexPool);
            int counter = 0;
            for (int i = 0; i < pool->maxNum && counter < NUMBER
                && pool->liveNum < pool->maxNum; ++i)
            {
                if (pool->threadIDs[i] == 0)
                {
                    pthread_create(&pool->threadIDs[i], NULL, worker, pool);
                    counter++;
                    pool->liveNum++;
                }
            }
            pthread_mutex_unlock(&pool->mutexPool);
        }
        // 销毁线程
        // 忙的线程*2 < 存活的线程数 && 存活的线程>最小线程数
        if (busyNum * 2 < liveNum && liveNum > pool->minNum)
        {
            pthread_mutex_lock(&pool->mutexPool);
            pool->exitNum = NUMBER;
            pthread_mutex_unlock(&pool->mutexPool);
            // 让工作的线程自杀
            for (int i = 0; i < NUMBER; ++i)
            {
                pthread_cond_signal(&pool->notEmpty);
            }
        }
    }
    return NULL;
}

void threadExit(ThreadPool* pool)
{
    pthread_t tid = pthread_self();
    for (int i = 0; i < pool->maxNum; ++i)
    {
        if (pool->threadIDs[i] == tid)
        {
            pool->threadIDs[i] = 0;
            printf("threadExit() called, %ld exiting...\n", tid);
            break;
        }
    }
    pthread_exit(NULL);
}

1.5 测试代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
void taskFunc(void* arg)
{
    int num = *(int*)arg;
    printf("thread %ld is working, number = %d\n",
        pthread_self(), num);
    sleep(1);
}

int main()
{
    // 创建线程池
    ThreadPool* pool = threadPoolCreate(3, 10, 100);
    for (int i = 0; i < 100; ++i)
    {
        int* num = (int*)malloc(sizeof(int));
        *num = i + 100;
        threadPoolAdd(pool, taskFunc, num);
    }

    sleep(30);

    threadPoolDestroy(pool);
    return 0;
}

2.C++版

视频教程点我查看

2.1 任务队列

2.1.1 类声明

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
// 定义任务结构体
using callback = void(*)(void*);
struct Task
{
    Task()
    {
        function = nullptr;
        arg = nullptr;
    }
    Task(callback f, void* arg)
    {
        function = f;
        this->arg = arg;
    }
    callback function;
    void* arg;
};

// 任务队列
class TaskQueue
{
public:
    TaskQueue();
    ~TaskQueue();

    // 添加任务
    void addTask(Task& task);
    void addTask(callback func, void* arg);

    // 取出一个任务
    Task takeTask();

    // 获取当前队列中任务个数
    inline int taskNumber()
    {
        return m_queue.size();
    }

private:
    pthread_mutex_t m_mutex;    // 互斥锁
    std::queue<Task> m_queue;   // 任务队列
};

其中 Task 是任务类，里边有两个成员，分别是两个指针 void(*)(void*)和 void*

另外一个类 TaskQueue 是任务队列，提供了添加任务、取出任务、存储任务、获取任务个数、线程同步的功能。

2.1.2 类定义

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
TaskQueue::TaskQueue()
{
    pthread_mutex_init(&m_mutex, NULL);
}

TaskQueue::~TaskQueue()
{
    pthread_mutex_destroy(&m_mutex);
}

void TaskQueue::addTask(Task& task)
{
    pthread_mutex_lock(&m_mutex);
    m_queue.push(task);
    pthread_mutex_unlock(&m_mutex);
}

void TaskQueue::addTask(callback func, void* arg)
{
    pthread_mutex_lock(&m_mutex);
    Task task;
    task.function = func;
    task.arg = arg;
    m_queue.push(task);
    pthread_mutex_unlock(&m_mutex);
}

Task TaskQueue::takeTask()
{
    Task t;
    pthread_mutex_lock(&m_mutex);
    if (m_queue.size() > 0)
    {
        t = m_queue.front();
        m_queue.pop();
    }
    pthread_mutex_unlock(&m_mutex);
    return t;
}

2.2 线程池

2.2.1 类声明

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
class ThreadPool
{
public:
    ThreadPool(int min, int max);
    ~ThreadPool();

    // 添加任务
    void addTask(Task task);
    // 获取忙线程的个数
    int getBusyNumber();
    // 获取活着的线程个数
    int getAliveNumber();

private:
    // 工作的线程的任务函数
    static void* worker(void* arg);
    // 管理者线程的任务函数
    static void* manager(void* arg);
    void threadExit();

private:
    pthread_mutex_t m_lock;
    pthread_cond_t m_notEmpty;
    pthread_t* m_threadIDs;
    pthread_t m_managerID;
    TaskQueue* m_taskQ;
    int m_minNum;
    int m_maxNum;
    int m_busyNum;
    int m_aliveNum;
    int m_exitNum;
    bool m_shutdown = false;
};

2.2.2 类定义

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
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
ThreadPool::ThreadPool(int minNum, int maxNum)
{
    // 实例化任务队列
    m_taskQ = new TaskQueue;
    do {
        // 初始化线程池
        m_minNum = minNum;
        m_maxNum = maxNum;
        m_busyNum = 0;
        m_aliveNum = minNum;

        // 根据线程的最大上限给线程数组分配内存
        m_threadIDs = new pthread_t[maxNum];
        if (m_threadIDs == nullptr)
        {
            cout << "malloc thread_t[] 失败...." << endl;;
            break;
        }
        // 初始化
        memset(m_threadIDs, 0, sizeof(pthread_t) * maxNum);
        // 初始化互斥锁,条件变量
        if (pthread_mutex_init(&m_lock, NULL) != 0 ||
            pthread_cond_init(&m_notEmpty, NULL) != 0)
        {
            cout << "init mutex or condition fail..." << endl;
            break;
        }

        /////////////////// 创建线程 //////////////////
        // 根据最小线程个数, 创建线程
        for (int i = 0; i < minNum; ++i)
        {
            pthread_create(&m_threadIDs[i], NULL, worker, this);
            cout << "创建子线程, ID: " << to_string(m_threadIDs[i]) << endl;
        }
        // 创建管理者线程, 1个
        pthread_create(&m_managerID, NULL, manager, this);
    } while (0);
}

ThreadPool::~ThreadPool()
{
    m_shutdown = 1;
    // 销毁管理者线程
    pthread_join(m_managerID, NULL);
    // 唤醒所有消费者线程
    for (int i = 0; i < m_aliveNum; ++i)
    {
        pthread_cond_signal(&m_notEmpty);
    }

    if (m_taskQ) delete m_taskQ;
    if (m_threadIDs) delete[]m_threadIDs;
    pthread_mutex_destroy(&m_lock);
    pthread_cond_destroy(&m_notEmpty);
}

void ThreadPool::addTask(Task task)
{
    if (m_shutdown)
    {
        return;
    }
    // 添加任务，不需要加锁，任务队列中有锁
    m_taskQ->addTask(task);
    // 唤醒工作的线程
    pthread_cond_signal(&m_notEmpty);
}

int ThreadPool::getAliveNumber()
{
    int threadNum = 0;
    pthread_mutex_lock(&m_lock);
    threadNum = m_aliveNum;
    pthread_mutex_unlock(&m_lock);
    return threadNum;
}

int ThreadPool::getBusyNumber()
{
    int busyNum = 0;
    pthread_mutex_lock(&m_lock);
    busyNum = m_busyNum;
    pthread_mutex_unlock(&m_lock);
    return busyNum;
}


// 工作线程任务函数
void* ThreadPool::worker(void* arg)
{
    ThreadPool* pool = static_cast<ThreadPool*>(arg);
    // 一直不停的工作
    while (true)
    {
        // 访问任务队列(共享资源)加锁
        pthread_mutex_lock(&pool->m_lock);
        // 判断任务队列是否为空, 如果为空工作线程阻塞
        while (pool->m_taskQ->taskNumber() == 0 && !pool->m_shutdown)
        {
            cout << "thread " << to_string(pthread_self()) << " waiting..." << endl;
            // 阻塞线程
            pthread_cond_wait(&pool->m_notEmpty, &pool->m_lock);

            // 解除阻塞之后, 判断是否要销毁线程
            if (pool->m_exitNum > 0)
            {
                pool->m_exitNum--;
                if (pool->m_aliveNum > pool->m_minNum)
                {
                    pool->m_aliveNum--;
                    pthread_mutex_unlock(&pool->m_lock);
                    pool->threadExit();
                }
            }
        }
        // 判断线程池是否被关闭了
        if (pool->m_shutdown)
        {
            pthread_mutex_unlock(&pool->m_lock);
            pool->threadExit();
        }

        // 从任务队列中取出一个任务
        Task task = pool->m_taskQ->takeTask();
        // 工作的线程+1
        pool->m_busyNum++;
        // 线程池解锁
        pthread_mutex_unlock(&pool->m_lock);
        // 执行任务
        cout << "thread " << to_string(pthread_self()) << " start working..." << endl;
        task.function(task.arg);
        delete task.arg;
        task.arg = nullptr;

        // 任务处理结束
        cout << "thread " << to_string(pthread_self()) << " end working...";
        pthread_mutex_lock(&pool->m_lock);
        pool->m_busyNum--;
        pthread_mutex_unlock(&pool->m_lock);
    }

    return nullptr;
}


// 管理者线程任务函数
void* ThreadPool::manager(void* arg)
{
    ThreadPool* pool = static_cast<ThreadPool*>(arg);
    // 如果线程池没有关闭, 就一直检测
    while (!pool->m_shutdown)
    {
        // 每隔5s检测一次
        sleep(5);
        // 取出线程池中的任务数和线程数量
        //  取出工作的线程池数量
        pthread_mutex_lock(&pool->m_lock);
        int queueSize = pool->m_taskQ->taskNumber();
        int liveNum = pool->m_aliveNum;
        int busyNum = pool->m_busyNum;
        pthread_mutex_unlock(&pool->m_lock);

        // 创建线程
        const int NUMBER = 2;
        // 当前任务个数>存活的线程数 && 存活的线程数<最大线程个数
        if (queueSize > liveNum && liveNum < pool->m_maxNum)
        {
            // 线程池加锁
            pthread_mutex_lock(&pool->m_lock);
            int num = 0;
            for (int i = 0; i < pool->m_maxNum && num < NUMBER
                && pool->m_aliveNum < pool->m_maxNum; ++i)
            {
                if (pool->m_threadIDs[i] == 0)
                {
                    pthread_create(&pool->m_threadIDs[i], NULL, worker, pool);
                    num++;
                    pool->m_aliveNum++;
                }
            }
            pthread_mutex_unlock(&pool->m_lock);
        }

        // 销毁多余的线程
        // 忙线程*2 < 存活的线程数目 && 存活的线程数 > 最小线程数量
        if (busyNum * 2 < liveNum && liveNum > pool->m_minNum)
        {
            pthread_mutex_lock(&pool->m_lock);
            pool->m_exitNum = NUMBER;
            pthread_mutex_unlock(&pool->m_lock);
            for (int i = 0; i < NUMBER; ++i)
            {
                pthread_cond_signal(&pool->m_notEmpty);
            }
        }
    }
    return nullptr;
}

// 线程退出
void ThreadPool::threadExit()
{
    pthread_t tid = pthread_self();
    for (int i = 0; i < m_maxNum; ++i)
    {
        if (m_threadIDs[i] == tid)
        {
            cout << "threadExit() function: thread " 
                << to_string(pthread_self()) << " exiting..." << endl;
            m_threadIDs[i] = 0;
            break;
        }
    }
    pthread_exit(NULL);
}