id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8323	boost::thread::try_join_for/try_join_until may block indefinitely due to a combination of problems in Boost.Thread and Boost.Chrono	szakharchenko@…	viboes	"In the following, try_join_test may hang indefinitely (using Boost 1.50):

{{{#!c++
void very_busy_thread()
{
    while (true) boost::this_thread::interruption_point();
}

void try_join_test()
{
    boost::thread t(very_busy_thread);
    for (int i=0;i<1000000;i++)
    {
        t.try_join_for(boost::chrono::milliseconds(0)); // This call may hang indefinitely
    }
    t.interrupt();
    t.join();
}

}}}

This has been reproduced on a real dual-core Intel Xeon system and also on 2 multicore virtual machines (one using VirtualBox, another with KVM).

Here's my (incomplete, possibly incorrect) analysis of the problem:

thread.try_join_for(boost::chrono::milliseconds(0)) called on thread which is still running
{{{#!c++
bool try_join_for(const chrono::duration<Rep, Period>& rel_time)
{
   return try_join_until(chrono::steady_clock::now() + rel_time);
}
}}}

steady_clock comes into play, which calls QueryPerformanceCounter the ""steadiness"" of which is disputable

here Clock is steady_clock

   t = rep_ = 5591678518200

   system_clock::time_point     s_now = system_clock::now() = rep_=130084071987844000;

   typename Clock::time_point  c_now = Clock::now() = rep_ = 5591679763370 which is LESS THAN t = rep_ = 5591678518200 (QueryPerformanceCounter says hello)

   try_join_until(s_now + ceil<nanoseconds>(t - c_now)) is called with a system time in the PAST AND in a past ~1msec ago (possibly important!)

thread.cpp:342:

{{{#!c++
   chrono::milliseconds rel_time= chrono::ceil<chrono::milliseconds>(tp-chrono::system_clock::now());
}}}

rel_time becomes EXACTLY -1;

detail::timeout(uintmax_t milliseconds_) accepts a _signed_ integer, converting it to a huge number;

target_time.is_sentinel() == false

target_time.remaining_milliseconds(), time_left.milliseconds > min_timer_wait_period is false (thread.cpp:482)

using_timer == false (not using SetWaitableTimer)

target_time becomes detail::timeout(time_left.milliseconds) (a huge number) (thread.cpp:501)

is_sentinel() returns true -> remaining_milliseconds returns remaining_time(win32::infinite) (thread_data.hpp:151)

time_left.milliseconds becomes a large number

using_timer is false, time_left.milliseconds is used as timeout which is huge

WaitForMultipleObjects waits for a nearly-infinite amount of time
"	Bugs	closed	Boost 1.54.0	thread	Boost 1.50.0	Problem	fixed	thread, chrono, steady_clock, try_jon_for, try_join_until, QueryPerformanceCounter