c – boost :: thread_sleep vs boost :: chrono :: thread_cloc

发布时间：2020-12-16 06:53:52 所属栏目：百科来源：网络整理

导读：当我运行此代码时 #include iostream#include boost/thread.hpp#include boost/chrono/thread_clock.hppvoid foo() { boost::this_thread::sleep(boost::posix_time::microseconds(500));}int main() { boost::chrono::thread_clock::time_point start = boo

当我运行此代码时

#include <iostream>
#include <boost/thread.hpp>
#include <boost/chrono/thread_clock.hpp>

void foo() {
    boost::this_thread::sleep(boost::posix_time::microseconds(500));
}


int main() {
    boost::chrono::thread_clock::time_point start = boost::chrono::thread_clock::now();    
    foo();   
    boost::chrono::thread_clock::time_point stop = boost::chrono::thread_clock::now();    
    std::cout << "duration = " 
              << boost::chrono::duration_cast<boost::chrono::microseconds>(stop-start).count() 
              << " microsecn";
}

我得到以下输出：

duration = 121 microsec
duration = 121 microsec
duration = 110 microsec
duration = 114 microsec

此外,当我用不同的值(例如200)替换500时,输出始终大约为100.使用-O3进行编译.为什么时机不一致？

PS：我读到睡眠已被弃用,但是当我用它替换它时

boost::this_thread::sleep_for(boost::chrono::microseconds(200));

输出在~20微秒的范围内.

解决方法

的确,我忽略了一些明显的事情 documentation说：

thread_clock class provides access to the real thread wall-clock,i.e.
the real CPU-time clock of the calling thread.

我认为wall-time是实时传递的,而不是cpu-time,它不包括线程休眠的时间.无论如何,为了获得一致的数字,我不得不使用boost :: chrono :: system_clock.

（编辑：李大同）

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