linux多线程的总结（pthread用法）
原创：lobbve223 出自: http://www.linuxdiyf.com
#include
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转函数的肇端地址。
第四个参数是运转函数的参数。
当创立线程成功时，函数前往0，若不为0则阐明');创立线程掉败，罕有的错误前往代码为EAGAIN和EINVAL。前者体现系统限制创立新的线程，例如线程数量过多了；后者体现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系统默许的库，所以在运用pthread_create创立线程时，须要在编译中请加-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 壅塞尝试的线程直到某线程完毕
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 Bye!
pthread_join()
void pthread_exit(void *retval)
int pthread_join(pthread_t pid, void **thread_return)
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）的前往值，若是thread_return不为NULL，则*thread_return=retval。
须要看重的是一个线程仅允许独一的另一个线程运用 pthread_join()等待本线程的终止，并且被等待的线程应该处于可join状况，即非DETACHED状况。
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