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: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2014-09-12 06:35:02

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?

Niall

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