Subject: Re: [boost] [thread] Timed waits in Boost.Thread potentiallyfundamentally broken on Windows (possibly rest of Boost too)
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2015-01-25 05:24:17
Le 24/01/15 20:56, Niall Douglas a écrit :
> On 24 Jan 2015 at 21:29, Andrey Semashev wrote:
>
>> And there's another consideration. Waitable timers are useful for
>> absolute waits. For relative waits I would still like Boost.Thread to
>> use relative system waits. The reason is that relative waits do not
>> react to system time shifts and do not require a waitable timer kernel
>> object.
> This is interesting actually. The win32 interruptible_wait() and
> uninterruptible_wait() functions consume a detail::timeout which is
> capable of transferring either relative or absolute timeout. However
> condition_variable timed wait and thread timed join never calls with
> anything but an absolute deadline timeout, and converts all relative
> to absolute. Oddly enough this_thread::sleep_until seems to convert
> its absolute timeout to a relative one, and thunks through
> this_thread::sleep_for, so here all absolutes are converted to
> relative.
>
> So we have the odd situation that condition_variable and thread join
> are always implemented as absolute timeouts, while thread sleep is
> always implemented as relative timeouts. I also see that timed mutex
> always converts absolute to relative too on win32.
>
> Some of this isn't win32 specific either. I can see some code there
> which looks like these are decisions being made by upper layers of
> code and so would affect POSIX as well.
>
> I've added this issue as
> https://svn.boost.org/trac/boost/ticket/10967.
>
> Some references to code:
>
> Always uses absolute:
> https://github.com/boostorg/thread/blob/develop/include/boost/thread/win32/condition_variable.hpp#L92
>
> Always uses relative:
> https://github.com/boostorg/thread/blob/develop/include/boost/thread/win32/basic_timed_mutex.hpp#L190
>
> Always uses relative:
> https://github.com/boostorg/thread/blob/develop/include/boost/thread/v2/thread.hpp#L60
>
> Always uses absolute:
> https://github.com/boostorg/thread/blob/develop/include/boost/thread/detail/thread.hpp#L551
>
>
Thanks Niall for this report.
As you know I'm unable to check on Windows. Please look at the ticket,
I'm here to contribute to fix this incoherences.
Best,
Vicente