- #include<pthread.h>
- int pthread_create(pthread_t *restrict tidp,const pthread_attr_t *restrict attr,
void *(*start_rtn)(void),void *restrict arg);
Returns 0 if OK, error number on failure,第一个参数为指向线程标识符的指针,第二个参数用来设置线程属性,第三个参数是线程运行函数的起始地址,第四个参数是运行函数的参数。
当创建线程成功时,函数返回0,若不为0则说明创建线程失败,常见的错误返回代码为EAGAIN和EINVAL。前者表示系统限制创建新的线程,例如线程数目过多了;后者表示第二个参数代表的线程属性值非法.pthread_create的用法:由于pthread库不是Linux系统默认的库,所以在使用pthread_create创建线程时,需要在编译中请加-lpthread参数,eg:gcc -o test -lpthrea test.c
例1:
- #include "pthread.h"
- #include "stdio.h"
- void* thread_test(void* ptr)
- {
- while(1)
- printf("i am pthread\n");
- }
- int main()
- {
- pthread_t pid;
- pthread_create(&pid, NULL, test_thread, NULL);
- while(1)
- printf("i am main pthread\n");
- return 0;
- }
例2:
- #include
- #include
- pthread_t id;
- int ret;
- void thread_1()
- {
- while(1)
- {
- printf(“I am thread\n”);
- sleep(1);
- }
- }
- main()
- {
- ret = pthread_create(&id,NULL,(void*)thread_1,NULL);
- if(ret != 0)
- printf("Create pthread error!\n");
- while(1)
- {
- printf(“I am main thread\n”);
- sleep(2);
- }
- }
例3:
- #include
- #include
- #include
- #include
- void *thread_function(void *arg);
- char message[] = "Hello World";
- int main()
- {
- int res;
- pthread_t a_thread;
- void *thread_result;
- res = pthread_create(&a_thread, NULL, thread_function, (void *)message);
- if (res != 0)
- {
- perror("Thread creation failed");
- exit(EXIT_FAILURE);
- }
- printf("Waiting for thread to finish...\n");
- res = pthread_join(a_thread, &thread_result); //pthread_join 阻塞执行的线程直到某线程结束
- if (res != 0)
- {
- perror("Thread join failed");
- exit(EXIT_FAILURE);
- }
- printf("Thread joined, it returned %s\n", (char *)thread_result);
- printf("Message is now %s\n", message);
- exit(EXIT_SUCCESS);
- }
- void *thread_function(void *arg)
- {
- printf("thread_function is running. Argument was %s\n", (char *)arg);
- sleep(3);
- strcpy(message, "Bye!");
- pthread_exit("Thank you for the CPU time");
- }
- [root@plinux tmp]# cc -D_REENTRANT -I/usr/include/nptl thread2.c -o thread2 -L/usr/lib/nptl -lpthread
- [root@plinux tmp]# ./thread2
- thread_function is running. Argument was Hello World
- Waiting for thread to finish...
- Thread joined, it returned Thank you for the CPU time
- Message is now
pthread_join的函数原型为int pthread_join(pthread_t pid, void **thread_return),pthread_exit的函数原型为void pthread_exit(void *retval),pthread_join()的调用者将挂起并等待th线程终止,retval是调用pthread_exit()的线程(线程ID为pid)的返回值,如果thread_return不为NULL,则*thread_return=retval。
需要注意的是一个线程仅允许唯一的另一个线程使用 pthread_join()等待本线程的终止,并且被等待的线程应该处于可join状态,即非DETACHED状态。
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