Re: [Boost-users] [Thread] thousands of spurious wakeups from timed_wait() per second

Subject: Re: [Boost-users] [Thread] thousands of spurious wakeups from timed_wait() per second
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2014-09-14 15:59:29

Le 12/09/14 12:35, Niall Douglas a écrit :
> On 11 Sep 2014 at 16:17, Steve Clark wrote:
>
>> I converted the test program to make pthread calls instead of Boost.  It
>> works perfectly, just like your Mac run.  This is unsatisfactory because
>> eventually I want the same code to run on Windows.
>>
>> I've been suspicious that timed_wait() isn't actually waiting at all - just
>> doing something like yield().  When I added a check for the current time vs.
>> the timeout deadline into my test program, the number of spurious wakeups
>> dropped almost to half, suggesting to me that the
>> boost::posix_time::microsec_clock::local_time() call almost doubles the time
>> it takes to run through the inner loop.
> Hmm. Maybe my timer changes on Windows for 1.56 are broken? I have to
> admit I relied on the unit test suite instead of manually checking I
> made the time calculations correctly. I believe there is a test in
> the unit test which checks that sleeping for a second really did take
> roughly a second.
>
> Can you test 1.55 or some earlier Boost?
>
>
It seems that the problem is present in 1.55 (see 
https://svn.boost.org/trac/boost/ticket/9856).

Niall please, could you try to reproduce it on Windows 1.55?

Best,
Vicente