Re: [Boost-users] Re: Q: Stopping threads (Win32) or... the mysterious case of the thread with split personality

From: Cory Nelson (phrosty_at_[hidden])
Date: 2004-12-05 16:58:58

Are you passing your functor with boost::ref when creating the thread?
 Otherwise it will make a copy.

On Sun, 5 Dec 2004 21:07:52 +0200, Dan Dimerman
<dimerman_at_[hidden]> wrote:
> Hello Jeffrey and thank you for your response,
> 
> As you point out, and is my general understanding, the thread indeed does
> kills itself by exiting its main loop. My question pointed more towards what
> you call "legit inter-thread" communication: I thought a shared variable
> would be enough, given there is only one state transition (true to false),
> just two threads and one is consistently the writer and the other
> consistently the reader. What I see (debugger) is that from inside one
> thread (main) the value of this variable is false, and from the other thread
> (worker) the value is different !
> 
> "Jeffrey Holle" <jeff.holle_at_[hidden]> wrote in message
> news:covlls$he0$1_at_sea.gmane.org...
> 
> 
> > First, a thread should kill itself.
> > Second, you should use legit inter-thread communication.
> > The request to commit suicide should be one of the things the thread pends
> > on.
> > Don't know boost.threads, but thats the general correct way to write a
> > multi-threaded application.
> >
> > Dan Dimerman wrote:
> >> Hello,
> >>
> >> I would like to ask the group if you know of an efficient and clean way
> >> to stop a thread.
> >> What I've been using till now was a while loop in the function
> >> operator()() given to the boost::thread when created, whose condition was
> >> a boolean data member. This boolean was the means to stop the thread,
> >> such that when it was turned off, the child thread would exit the while
> >> loop and join the main thread.
> >> I am seeing now that this data member is being held twice (one copy for
> >> the main thread and one copy for the child thread) and there's no synch
> >> between the two copies; so when the main thread turns it off / false, the
> >> child thread goes on (since its copy is still on / true) and hell breaks
> >> loose.
> >>
> >> I am using VC7 in debug mode, so I started looking for some kind of
> >> flag/optimization I might be inadvertently using that makes data members
> >> into registers (thus explaining the copies), but couldn't find anything
> >> of the sort.
> >>
> >> Any help will be greatly appreciated...
> >>
> >> Dan
> >>
> >>
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-- 
Cory Nelson
http://www.int64.org