[Boost-bugs] [Boost C++ Libraries] #9856: condition_variable::wait_for returns wrong cv_status on timeout.

Subject: [Boost-bugs] [Boost C++ Libraries] #9856: condition_variable::wait_for returns wrong cv_status on timeout.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-04-08 18:39:24

#9856: condition_variable::wait_for returns wrong cv_status on timeout.
---------------------------------------------------+----------------------
 Reporter:  pi88el@…                               |      Owner:  anthonyw
     Type:  Bugs                                   |     Status:  new
Milestone:  To Be Determined                       |  Component:  thread
  Version:  Boost 1.55.0                           |   Severity:  Problem
 Keywords:  condition_variable wait_for cv_status  |
---------------------------------------------------+----------------------
 '''The following bug seems to work on *nix systems. But not on Windows 7
 with Visual Studio 2013 Express.'''[[BR]]
 If a condition variable is waiting for a defined amount of time, sometimes
 (nearly always) the returned cv_status is wrong.

 {{{
 int main() {
     mutex mtx;
     condition_variable cond;

     unique_lock<mutex> lk(mtx);

     std::cout << BOOST_VERSION << "\n";

     for(int i=0; i<10; i++) {
         std::cout << i << " : " << chrono::steady_clock::now() << "\n";
         if (cv_status::no_timeout == cond.wait_for(lk,
 chrono::seconds(1)))
             std::cout << "no_timeout\n";
     }
 }
 }}}

 While the condition is '''never''' notified, i get '''no_timeout'''.[[BR]]

 debuging the code:

 {{{
 steady_clock::time_point c_now = steady_clock::now();
 do_wait(lock, ceil<milliseconds>(d).count());
 return steady_clock::now() - c_now < d ? cv_status::no_timeout :
                                          cv_status::timeout;
 }}}

 '''steady_clock::now() - c_now < d''' is ''true''. It seems do_wait is
 sleeping to short.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9856>
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