深入Pthread(五):线程属性
线程属性相关API
phtread_attr_t attr;
int pthread_attr_init(pthread_attr_t* attr);
int pthread_attr_destroy(pthread_attr_t* attr);
int pthread_attr_getdetachstate(pthread_attr_t* attr, int* detachstate);
int pthread_attr_setdetachstate(pthread_attr_t* attr, int detachstate);
#ifdef _POSIX_THREAD_ATTR_STACKSIZE
int pthread_attr_getstacksize(pthread_attr_t* attr, size_t* stacksize);
int pthread_attr_setstacksize(pthread_attr_t* attr, size_t stacksize);
#endif
#ifdef _POSIX_THREAD_ATTR_STACKADDR
int pthread_attr_getstackaddr(pthread_attr_t* attr, void* stackaddr);
int pthread_attr_setstackaddr(pthread_attr_t* attr, void** stackaddr);
#endif
线程属性
POSIX定义的线程属性有:可分离状态(detachstate), 线程栈大小(stacksize),线程栈地址( stackaddr),作用域(scope), 继承调度(inheritsched), 调度策略(schedpolicy)和调度参数( schedparam)。 有些系统并不支持所有这些属性,使用前注意查看系统文档。
但是所有Pthread系统都支持detachstate属性,该属性可以是PTHREAD_CREATE_JOINABLE或PTHREAD_CREATE_DETACHED,默认的是joinable的。拥有joinable属性的线程可以被另外一个线程等待,同时还可以获得线程的返回值,然后被回收。而detached的线程结束时,使用的资源立马就会释放,不用其他线程等待。
线程stacksize属性移植性不是很好,若你的系统定义了_POSIX_THREAD_ATTR_STACKSIZE ,才可以调用api设定线程堆栈大小。Pthreads规定线程堆栈大小必须大于等于PTHREAD_STACK_MIN。
线程stackaddr属性移植性相当不好,若系统定义了_POSIX_THREAD_ATTR_STACKADDR,才可以调用api设定线程堆栈地址,指定一块内存区域,这块内存区域大小至少是PTHREAD_STACK_MIN。机器堆栈向上增长的,必须指定为低地址;机器堆栈向下增长的,必须指定为高地址。这个属性,最好不要用。
例程:
- #include <pthread.h>
- #include "error.h"
- #include <limits.h>
-
- pthread_attr_t attr;
-
-
- void* thread_routine(void* arg)
- {
- sleep(1);
- #ifdef _POSIX_THREAD_ATTR_STACKSIZE
- size_t stacksize;
- int status = pthread_attr_getstacksize(&attr, &stacksize);
- printf("[stacksize:%lu]thread routine is running..../n",stacksize);
- #endif
-
- return NULL;
- }
-
- int main()
- {
- pthread_t pid;
- int status;
- size_t stacksize;
- status = pthread_attr_init(&attr);
- if(status != 0)
- ERROR_ABORT(status,"Init attr");
-
- status = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
- if(status != 0)
- ERROR_ABORT(status, "Set detachstate");
-
- #ifdef _POSIX_THREAD_ATTR_STACKSIZE
- status = pthread_attr_getstacksize(&attr, &stacksize);
- if(status != 0)
- ERROR_ABORT(status, "Get stacksize");
- printf("Original thread size:%lu/n", stacksize);
-
- status = pthread_attr_setstacksize(&attr, 2*PTHREAD_STACK_MIN);
- if(status != 0)
- ERROR_ABORT(status, "Set stacksize");
- #endif
-
- status = pthread_create(&pid, &attr, thread_routine, NULL);
- if(status !=0 )
- ERROR_ABORT(status, "Create thread");
-
- status = pthread_attr_destroy(&attr);
- if(status != 0)
- ERROR_ABORT(status, "Destroy attr");
-
- printf("Main thread is over.../n");
- pthread_exit(NULL);
- }