Subject: [Boost-bugs] [Boost C++ Libraries] #11331: boost::this_thread::sleep_for does not sleep for requested time
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-05-21 23:01:15
#11331: boost::this_thread::sleep_for does not sleep for requested time
-----------------------------------------+----------------------
Reporter: Scott Minor <scott.minor@â¦> | Owner: anthonyw
Type: Bugs | Status: new
Milestone: To Be Determined | Component: thread
Version: Boost 1.58.0 | Severity: Problem
Keywords: sleep_for |
-----------------------------------------+----------------------
boost::this_thread::sleep_for does not accurately sleep for the requested
amount of time (+/- 30ms) on a Windows 7 x64 environment when the
requested time is on the order of half a minute.
std::this_thread::sleep_for is able to accurately sleep for the requested
amount of time. Here is a sample program illustrating the issue:
{{{
#include <boost/thread.hpp>
#include <boost/chrono.hpp>
#include <chrono>
#include <iostream>
#include <thread>
void boostThreadFunction ()
{
std::cout << "Starting Boost thread" << std::endl;
for (int i = 0; i < 10; ++i)
{
auto sleep_time = boost::chrono::milliseconds {29000 + 100 * i};
auto mark = std::chrono::steady_clock::now ();
boost::this_thread::sleep_for (sleep_time);
auto duration =
std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now () - mark);
std::cout << "Boost thread:" << std::endl;
std::cout << "\tSupposed to sleep for:\t" << sleep_time.count () <<
" ms" << std::endl;
std::cout << "\tActually slept for:\t" << duration.count () << " ms"
<< std::endl << std::endl;
}
}
void stdThreadFunction ()
{
std::cout << "Starting Std thread" << std::endl;
for (int i = 0; i < 10; ++i)
{
auto sleep_time = std::chrono::milliseconds {29000 + 100 * i};
auto mark = std::chrono::steady_clock::now ();
std::this_thread::sleep_for (sleep_time);
auto duration =
std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now () - mark);
std::cout << "Std thread:" << std::endl;
std::cout << "\tSupposed to sleep for:\t" << sleep_time.count () <<
" ms" << std::endl;
std::cout << "\tActually slept for:\t" << duration.count () << " ms"
<< std::endl << std::endl;
}
}
int main ()
{
boost::thread boost_thread (&boostThreadFunction);
std::this_thread::sleep_for (std::chrono::seconds (10));
std::thread std_thread (&stdThreadFunction);
boost_thread.join ();
std_thread.join ();
system ("pause");
return 0;
}
}}}
Here is the output produced in my environment:
{{{
Starting Boost thread
Starting Std thread
Boost thread:
Supposed to sleep for: 29000 ms
Actually slept for: 29690 ms
Std thread:
Supposed to sleep for: 29000 ms
Actually slept for: 29009 ms
Boost thread:
Supposed to sleep for: 29100 ms
Actually slept for: 29999 ms
Std thread:
Supposed to sleep for: 29100 ms
Actually slept for: 29111 ms
Boost thread:
Supposed to sleep for: 29200 ms
Actually slept for: 29990 ms
Std thread:
Supposed to sleep for: 29200 ms
Actually slept for: 29172 ms
Boost thread:
Supposed to sleep for: 29300 ms
Actually slept for: 30005 ms
Std thread:
Supposed to sleep for: 29300 ms
Actually slept for: 29339 ms
Boost thread:
Supposed to sleep for: 29400 ms
Actually slept for: 30003 ms
Std thread:
Supposed to sleep for: 29400 ms
Actually slept for: 29405 ms
Boost thread:
Supposed to sleep for: 29500 ms
Actually slept for: 29999 ms
Std thread:
Supposed to sleep for: 29500 ms
Actually slept for: 29472 ms
Boost thread:
Supposed to sleep for: 29600 ms
Actually slept for: 29999 ms
Std thread:
Supposed to sleep for: 29600 ms
Actually slept for: 29645 ms
Boost thread:
Supposed to sleep for: 29700 ms
Actually slept for: 29998 ms
Std thread:
Supposed to sleep for: 29700 ms
Actually slept for: 29706 ms
Boost thread:
Supposed to sleep for: 29800 ms
Actually slept for: 29998 ms
Std thread:
Supposed to sleep for: 29800 ms
Actually slept for: 29807 ms
Boost thread:
Supposed to sleep for: 29900 ms
Actually slept for: 30014 ms
Std thread:
Supposed to sleep for: 29900 ms
Actually slept for: 29915 ms
}}}
Looking at libs/thread/src/win32/thread.cpp, this inaccuracy may be by
design; a +/-5% tolerance appears to be added to the wait time to take
advantage of coalescing timers. See related StackOverflow question:
http://stackoverflow.com/questions/30381866/boost-thread-wakes-up-too-
late-in-1-58
However, we are dependent on sleep_for() being as accurate as possible;
for us, this is a breaking change.
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/11331> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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