取消线程:
功能:取消一个正在执行线程的操作。一个线程能够被取消需要满足条件
条件:一:该线程是否可以被其他取消是可设置的,
PTHREAD_CANCEL_DISABLE PTHREAD_CANCEL_ENABLE
二:该线程处于可取消点才能取消typedef unsigned long pthread_t // %lu
需要在 可取消状态 PTHREAD_CANCEL_ENABLE 是,才能被取消
extern int pthread_cancel (pthread_t __cancelthread)
设置可取消状态
查询当前线程的可取消性状态
extern int pthread_setcancelstate(int __state, int *__oldstate);
设置取消类型
extern int pthread_setcanceltype(int __type,int *__oldstate)
type = PTHREAD_CANCEL_ENABLE
type = PTHREAD_CANCEL_DISABLE函数描述:
主线程使用 pthread_cancle 取消线程。但是在子线程中用 pthread_setcancelstate 设置了 PTHREAD_CANCEL_DISABLE, 所以不能被取消,主线程处于等待状态。经过一段时间,子线程 设置为
PTHREAD_CANCEL_ENABLE ,现在就可以取消子线程操作了,主线程就取消了子线程的运行代码: pthread_cancel.rar gcc main.c -lpthread -o main- #include <stdio.h>
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#include <stdlib.h>
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#include <pthread.h>
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void *thread_fun(void *a);
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int main(int argc, char *argv[])
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{
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int res;
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pthread_t a_thread;//typedef unsigned long pthread_t &lu
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void *thread_result;
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res = pthread_create(&a_thread, NULL, (void *)*thread_fun, NULL); //建立子线程
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if(res != 0)
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{
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perror("thread create failed");
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exit(1);
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}
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sleep(10);
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printf("cancle thread...\n");
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res = pthread_cancel(a_thread); //取消子线程
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if(res != 0)
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{
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perror("thread cancle failed");
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exit(1);
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}
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printf("waiting for thread to finish...\n");
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res = pthread_join(a_thread, &thread_result); //退出 子线程
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if(res != 0)
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{
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perror("thread join failed");
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exit(1);
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}
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exit(EXIT_SUCCESS);
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}
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void *thread_fun(void *a)
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{
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int i,res,j; //存放在 栈中 临时变量
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sleep(1);
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res = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL); //设置取消状态 DISABLE
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if(res != 0)
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{
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perror("pthread setcanclestate failed");
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exit(EXIT_FAILURE);
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}
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sleep(3);
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printf("thread cancel type is disable ,can't cancle this thread\n"); //打印不可取状态信息
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for(i = 0; i < 3; i++)
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{
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printf("thread is running(%d)...\n",i);
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sleep(1);
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}
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res = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
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if(res != 0)
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{
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perror("pthread_setcanclestat failed");
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exit(EXIT_FAILURE);
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}
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else
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{
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printf("now change the canclestate is ENABLE\n");
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}
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sleep(200);
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pthread_exit(NULL); //没有返回到 主线程信息
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}
- ywx@yuweixian:~/yu/professional/4$ ./pthread_cancel
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thread cancel type is disable ,can't cancle this thread
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thread is running(0)...
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thread is running(1)...
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thread is running(2)...
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now change the canclestate is ENABLE
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cancle thread...
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waiting for thread to finish...
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