Re: [boost] Subject: Formal Review of Proposed Boost.Process library starts tomorrow

Subject: Re: [boost] Subject: Formal Review of Proposed Boost.Process library starts tomorrow
From: Artyom (artyomtnk_at_[hidden])
Date: 2011-02-10 14:54:25

> > So basically such  thread need
> > 
> >    forever (
> >       sigwait(sigchld)
> >      foreach pid in waiting  set
> >         if(waitpid(pid, WNOHANG) =  done)
> >            notify  io_service
> >            remove pid from  waiting set
> >    }
> 
> you iterate over the complete set of  pids you are waiting for. why not
> let waitpid( -1,...) let tell which child  has changed its status.
> 

Because it can accidentally catch an exit code of normal wait
for example consider that other thread waits synchronously,
this was the problem I've told in the original review notes
the race condition between waiting thread and other thread
that makes synchornous wait.

This is why you can't use waitpid with -1 or wait that
catches any child.

> Shouldn't the wait-functionality be  interrupt-able?
> How to do a grace full shutdown if forever  blocking?
> 

It can be done with other signal - you can use real-time
signals to notify the thread on interruption.

Artyom