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循环创建n个子线程

并 循环回收—难点

1-loop-pthread.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// 循环创建子线程, 并验证 是不是共享全局变量int var = 100;void *tfn(void *arg)
{int i = (int)arg;var = 400;printf("thread--%d: pid = %d, tid is %lu, var = %d\n", i, getpid(), pthread_self(), var);sleep(2);printf("test ----%d\n", i);return NULL; 
}int main(int argc, char *argv[])
{   pthread_t tid;int i=0;var = 200;while(i<10){int ret = pthread_create(&tid, NULL, tfn, (void*)i);// int ret = pthread_create(&tid, NULL, tfn, (void*)&i);   // 容易导致 内容错乱if(ret < 0){fprintf(stderr, "pthread error: %s\n", strerror(ret));exit(1);}i++;sleep(1);}printf("main: pid is %d, tid is %lu, var = %d\n", getpid(), pthread_self(), var);pthread_exit((void*)0);  // 会退出 当前线程, 也就是只退出了 主线程// return 0;//线程不能使用这个   会出现 子线程还未结束, 整体 进程 就退出
}

2-pthread-join-error.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// pthread_join 测试
// 错误示范, 局部变量 地址 会被释放, 所以一直返回 0int var = 100;void *tfn(void *arg)
{int i = (int)arg;var = 400;printf("thread--%d: pid = %d, tid is %lu, var = %d\n", i, getpid(), pthread_self(), var);sleep(2);printf("test ----%d\n", i);int *r=&i;return (void*)r; 
}int main(int argc, char *argv[])
{   pthread_t tid;int i=0;var = 200;int *tidret;  while(i<10){int ret = pthread_create(&tid, NULL, tfn, (void*)i);if(ret < 0){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}ret = pthread_join(tid, (void **)&tidret);if(ret < 0){fprintf(stderr, "pthread_join error: %s\n", strerror(ret));exit(1);}printf("child %d return %d\n",i, *tidret);i++;sleep(1);}printf("main: pid is %d, tid is %lu, var = %d\n", getpid(), pthread_self(), var);pthread_exit((void*)0);  // 会退出 当前线程, 也就是只退出了 主线程// return 0;//线程不能使用这个   会出现 子线程还未结束, 整体 进程 就退出
}

3-pthread-join-true.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// pthread_join 测试
// 错误示范, 局部变量 地址 会被释放, 所以一直返回 0
// 这是正确示范   使用malloc 可以防止销毁int var = 100;void *tfn(void *arg)
{int i = (int)arg;var = 400;printf("thread--%d: pid = %d, tid is %lu, var = %d\n", i, getpid(), pthread_self(), var);sleep(1);printf("test ----%d\n", i);int *r = malloc(sizeof(int *));   *r = i;   // 不能传地址, 地址会释放, 传递值  注意不是  r=ireturn (void*)r; 
}int main(int argc, char *argv[])
{   pthread_t tid;int i=0;var = 200;// int *tidret;   // 外部容易 内存 泄漏while(i<10){int *tidret; int ret = pthread_create(&tid, NULL, tfn, (void*)i);if(ret < 0){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}ret = pthread_join(tid, (void **)&tidret);if(ret < 0){fprintf(stderr, "pthread_join error: %s\n", strerror(ret));exit(1);}printf("child %d return %d\n",i, *tidret);free(tidret);i++;sleep(1);}printf("main: pid is %d, tid is %lu, var = %d\n", getpid(), pthread_self(), var);pthread_exit((void*)0);  // 会退出 当前线程, 也就是只退出了 主线程// return 0;//线程不能使用这个   会出现 子线程还未结束, 整体 进程 就退出
}

使用 pthread_cancel函数取消线程

使用默认系统调用 作为取消点

使用 指定的pthread_testcancel()作为取消点

pthread-cancel.c

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <stdlib.h>
void *tfn1(void *arg)
{printf("thread 1 returning\n");return (void *)111;
}
void *tfn2(void *arg)
{printf("thread 2 exiting\n");pthread_exit((void *)222);
}
void *tfn3(void *arg)
{while (1){// printf("thread 3: I'm going to die in 3 seconds ...\n");  // sleep(1); //这两句 会进入系统调用, 到达 取消点, 若没有这两句, 需手动添加取消点pthread_testcancel(); //自己添加取消点*/}return (void *)666;
}
int main(void)
{pthread_t tid;void *tret = NULL;pthread_create(&tid, NULL, tfn1, NULL);pthread_join(tid, &tret);printf("thread 1 exit code = %d\n\n", (int)tret);pthread_create(&tid, NULL, tfn2, NULL);pthread_join(tid, &tret);printf("thread 2 exit code = %d\n\n", (int)tret);pthread_create(&tid, NULL, tfn3, NULL);sleep(3);pthread_cancel(tid);pthread_join(tid, &tret);printf("thread 3 exit code = %d\n", (int)tret);return 0;
}

设置 线程分离, 并 jion回收, 查看出错

pthread-detach.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>void *tf(void *arg)
{printf("exit ----- \n");return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid;int ret = pthread_create(&tid, NULL, tf, NULL);if(ret != 0){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}ret = pthread_detach(tid);if(ret != 0){fprintf(stderr, "pthread_detach error: %s\n", strerror(ret));exit(1);}sleep(2);  // 不等待,看不出区别ret = pthread_join(tid, NULL);if(ret != 0){fprintf(stderr, "pthread_join error: %s\n", strerror(ret));exit(1);}printf("main----\n");pthread_exit(NULL);
}

使用线程 属性设置 分离态

pthread-attr.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>void *fn(void *arg)
{printf("child-----\n");return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid;pthread_attr_t attr;pthread_attr_init(&attr);pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);int ret = pthread_create(&tid, &attr, fn, NULL);if(ret != 0){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}ret = pthread_join(tid, NULL);if(ret != 0){fprintf(stderr, "pthread_join error: %s\n", strerror(ret));exit(1);}pthread_attr_destroy(&attr);pthread_exit(NULL);
}

简单的 互斥锁(4个)

读写锁差不多,不写案例

不使用锁的效果

正常加锁解锁

tyrlock 替换进去看效果

营造死锁的 问题

1-mutex-no-lock.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// 无锁, 多个线程 会抢占资源, 不能按照顺序打印void *fn(void *arg)
{while(1){printf("hello--2\n");sleep(rand()%3);printf("world--2\n");sleep(rand()%3);}return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid;srand(time(NULL));int ret = pthread_create(&tid, NULL, fn, NULL);if(ret < 0 ){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}while(1){printf("HELLO--1\n");sleep(rand()%3);printf("WORLD--1\n");sleep(rand()%3);}pthread_join(tid, NULL);pthread_exit(NULL);}

2-mutex-lock.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// 无锁, 多个线程 会抢占资源, 不能按照顺序打印
// 加锁,  会 一个线程 一会占用 pthread_mutex_t mutex;  // 定义一个全局, 可以使得 所有线程 都能加锁解锁void *fn(void *arg)
{while(1){pthread_mutex_lock(&mutex);printf("hello--2\n");sleep(rand()%3);printf("world--2\n");pthread_mutex_unlock(&mutex);sleep(rand()%3);}return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid;srand(time(NULL));pthread_mutex_init(&mutex, NULL);int ret = pthread_create(&tid, NULL, fn, NULL);if(ret < 0 ){fprintf(stderr, "pthread_create error: %s\n", strerror(ret));exit(1);}while(1){pthread_mutex_lock(&mutex);printf("HELLO--1\n");sleep(rand()%3);printf("WORLD--1\n");pthread_mutex_unlock(&mutex);sleep(rand()%3);}pthread_join(tid, NULL);pthread_mutex_destroy(&mutex);pthread_exit(NULL);}

3-mutex-trylock.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// 无锁, 多个线程 会抢占资源, 不能按照顺序打印
// 加锁,  会 一个线程 一会占用 pthread_mutex_t mutex;  // 定义一个全局, 可以使得 所有线程 都能加锁解锁void *fn(void *arg)
{if((pthread_mutex_trylock(&mutex) == 0)){printf("thread %ld: acquire lock\n", (long)arg);sleep(2);pthread_mutex_unlock(&mutex);}else{printf("thread %ld: none lock\n", (long)arg);}return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid,tid2;srand(time(NULL));pthread_mutex_init(&mutex, NULL);int ret = pthread_create(&tid, NULL, fn, (void *)1);pthread_join(tid, NULL);   // 这个位置决定了 1结束, 2才会创建, 因此都会打印 拿到锁ret = pthread_create(&tid2, NULL, fn, (void *)2);// pthread_join(tid, NULL);pthread_join(tid2, NULL);pthread_mutex_destroy(&mutex);pthread_exit(NULL);}

4-mutex-si.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>// 反复加锁, 会死锁, 一直阻塞pthread_mutex_t mutex;  // 定义一个全局, 可以使得 所有线程 都能加锁解锁void *fn(void *arg)
{if((pthread_mutex_lock(&mutex) == 0)){printf("thread %ld: acquire lock\n", (long)arg);sleep(2);// pthread_mutex_unlock(&mutex);}else{printf("thread %ld: none lock\n", (long)arg);}return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid,tid2;srand(time(NULL));pthread_mutex_init(&mutex, NULL);int ret = pthread_create(&tid, NULL, fn, (void *)1);pthread_join(tid, NULL);   // 这个位置决定了 1结束, 2才会创建, 因此都会打印 拿到锁ret = pthread_create(&tid2, NULL, fn, (void *)2);// pthread_join(tid, NULL);pthread_join(tid2, NULL);pthread_mutex_destroy(&mutex);pthread_exit(NULL);}

条件变量—重点

生产者和消费者模型

producer-customer.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>pthread_mutex_t mutex;
pthread_cond_t cond_product;struct product *head;
int i=10,j=10;
struct product
{int num;struct product *next;
};void Prr(int ret, char *str)
{if(ret < 0){fprintf(stderr, "%s error : %s\n",str, strerror(ret));exit(1);}
}void *Customer(void *arg)
{struct product *stc;while(i!=0){pthread_mutex_lock(&mutex); while(head == NULL) // 为空, 则条件变量, 阻塞等待   不使用if, 解除阻塞后, 需要再次检查, 若是多个customer, 可能为空{pthread_cond_wait(&cond_product, &mutex);}stc = head;head = head->next;printf("customer ------ %d\n", stc->num);free(stc);pthread_mutex_unlock(&mutex);sleep(rand()%4);i--;}return NULL;
}void *Productor(void *arg)
{struct product *st;while(j!=0){st = malloc(sizeof(struct product));st->num = rand()%1000;printf("product ------ %d\n", st->num);pthread_mutex_lock(&mutex);  // st 链表作为 共享资源, 因此改变链表需要加锁st->next = head;head = st;  // 头插法 head要一直保持在 开头,  新元素 next先指向head, head再指向新元素pthread_mutex_unlock(&mutex);pthread_cond_signal(&cond_product);  // 解锁并 唤醒sleep(rand()%4);j--;}return NULL;
}int main(int argc, char *argv[])
{   pthread_t tid1,tid2;int ret = pthread_create(&tid1, NULL, Productor, NULL);  // 生产和消费的顺序, 决定了 在哪里  mallocPrr(ret,"create");ret = pthread_create(&tid2, NULL, Customer, NULL);Prr(ret, "create");pthread_join(tid1, NULL);pthread_join(tid2, NULL);pthread_mutex_destroy(&mutex);pthread_cond_destroy(&cond_product);pthread_exit(NULL);
}