Re: [boost] [thread] Do we need thread_group now?

Subject: Re: [boost] [thread] Do we need thread_group now?
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2012-04-16 08:47:06

Vicente J. Botet wrote:
> Le 14/04/12 01:12, Howard Hinnant a écrit :
> > On Apr 10, 2012, at 1:32 PM, Vicente J. Botet Escriba
> > wrote:
> >
> >>     join_all(threads);
> > Is it worth the electrons to turn this into an algorithm?
> >
> >      std::for_each(threads.begin(), threads.end(),
> >                    [](thread&  t) {t.join();});
> >
> > or even simpler (really I think std::for_each is probably
> > obsolete):
> >
> >      for (auto&  t : threads)
> >          t.join();
>
> you are right for join_all and for c++11 compilers. But in
> order to make the code portable, join_all could help.

A newcomer to the library will not know what the correct formulation is to join all threads, or even that such a thing is possible or appropriate.  There will be other variations than those you've shown for joining all threads in a container, which makes joining code less obvious.  An algorithm provides a means to readable code, without variation, that immediately conveys the caller's intent.  Add portability to the mix and providing join_all makes a lot of sense.

> In addition, Boost.Thread provides timed join functions and I
> suspect that joining N threads for a given duration is less
> evident and subject to error on the user side.

Yet another reason to provide join_all: symmetry.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com

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