Pthread编程-设置/获取线程属性

Pthread编程-设置/获取线程属性

文章介绍如何设置/获取线程属性。与线程属性相关的函数大都以 pthread_attr_*开头，pthread_attr_get*用于获取线程属性，pthread_attr_get*用于设置线程属性。

这里仅罗列一些比较常用函数：

pthread_attr_init //初始化线程属性变量

pthread_attr_getstackaddr, pthread_attr_setstackaddr //栈地址（已废弃）

pthread_attr_getstacksize, pthread_attr_setstacksize //栈大小

pthread_attr_setguardsize, pthread_attr_getguardsize //保护区大小

pthread_attr_getdetachstate, pthread_attr_setdetachstate //分离属性

pthread_attr_getschedparam, pthread_attr_setschedparam //调度策略变量

pthread_attr_getschedpolicy, pthread_attr_setschedpolicy //调度策略

pthread_attr_getinheritsched, pthread_attr_setinheritsched //继承调度策略

pthread_attr_getscope, pthread_attr_setscope //线程调度竞争范围

pthread_setconcurrency, pthread_getconcurrency //并发级别

pthread_attr_destroy //销毁线程属性变量

其中：

pthread_attr_init()函数初始化线程属性变量为默认值；

pthread_attr_destroy()函数负责销毁线程属性变量

pthread_attr_set*()函数设置对应的线程属性的值

pthread_attr_get*()函数获取对应的线程属性的值

这里只是简单的罗列函数，具体使用可以参考 man function

下面提供一个测试程序：

#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include <pthread.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define ERROR(func, ret) {\
fprintf(stderr, "%s: %s\n", func, strerror(ret)); \
exit(EXIT_FAILURE); \
}

int main(int argc, char** argv)
{
pthread_attr_t attr;
pthread_attr_init(&attr);

int ret;
int state;
ret = pthread_attr_getdetachstate(&attr, &state);
if(0 != ret) {
ERROR("pthread_attr_getdetachstate", ret);
} else {
if(PTHREAD_CREATE_JOINABLE == state)
printf("pthread_attr_getdetachstate: PTHREAD_CREATE_JOINABLE\n");
else if(PTHREAD_CREATE_DETACHED == state)
printf("pthread_attr_getdetachstate: PTHREAD_CREATE_DETACHED\n");
}

void* stackaddr = malloc(PTHREAD_STACK_MIN);
//printf("stackaddr= %p\n", stackaddr);
ret = pthread_attr_getstackaddr(&attr, &stackaddr);
if(0 != ret) {
ERROR("pthread_attr_getstackaddr", ret);
} else {
printf("pthread_attr_getstackaddr: %p\n", stackaddr);
}
free(stackaddr);
stackaddr = NULL;

size_t size;
ret = pthread_attr_getstacksize(&attr, &size);
if(0 != ret) {
ERROR("pthread_attr_getstacksize", ret);
} else {
printf("pthread_attr_getstacksize: %lu\n", size);
}

ret = pthread_attr_getguardsize(&attr, &size);
if(0 != ret) {
ERROR("pthread_attr_getguardsize", ret);
} else {
printf("pthread_attr_getguardsize: %lu\n", size);
}

int scope;
ret = pthread_attr_getscope(&attr, &scope);
if(0 != ret) {
ERROR("pthread_attr_getscope", ret);
} else {
if(PTHREAD_SCOPE_PROCESS == scope)
printf("pthread_attr_getscope: PTHREAD_SCOPE_PROCESS\n");
else if(PTHREAD_SCOPE_SYSTEM == scope)
printf("pthread_attr_getscope: PTHREAD_SCOPE_SYSTEM\n");
}

int policy;
ret = pthread_attr_getschedpolicy(&attr, &policy);
if(0 != ret) {
ERROR("pthread_attr_getchedpolicy", ret);
} else {
if(SCHED_FIFO == policy)
printf("pthread_attr_getschedpolicy: SCHED_FIFO\n");
else if(SCHED_RR == policy)
printf("pthread_attr_getschedpolicy: SCHED_RR\n");
else if(SCHED_OTHER == policy)
printf("pthread_attr_getschedpolicy: SCHED_OTHER\n");
}

int schedinherited;
ret = pthread_attr_getinheritsched(&attr, &schedinherited);
if(0 != ret) {
ERROR("pthread_attr_getinheritsched", ret);
} else {
if(PTHREAD_INHERIT_SCHED == schedinherited)
printf("pthread_attr_getinheritsched: PTHREAD_INHERIT_SCHED\n");
else if(PTHREAD_EXPLICIT_SCHED == schedinherited)
printf("pthread_attr_getinheritsched: PTHREAD_EXPLICIT_SCHED\n");
}

struct sched_param param;
ret = pthread_attr_getschedparam(&attr, ¶m);
if(0 != ret) {
ERROR("pthread_attr_getschedparam", ret);
} else {
printf("pthread_attr_getschedparam: sched_priority %d\n",
param.sched_priority);
}

pthread_attr_destroy(&attr);

int level;
ret = pthread_getcon
b53e
currency();
if(0 != ret) {
ERROR("pthread_attr_getconcurrency", ret);
} else {
printf("pthread_getconcurrency: level %d\n", level);
}

exit(EXIT_SUCCESS);
}

编译运行：

gcc -o proc demo2.c -lpthread



PS: pthread_attr_*函数出错时不会修改全局变量 errno，出错处理时要注意。测试程序只调用 pthread_attr_ get* 函数获取线程的默认属性，pthread_attr_ set*函数调用类似，只不过一般情况下程序使用属性的默认值。