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

From: Dan Dimerman (dimerman_at_[hidden])
Date: 2004-12-06 05:35:23

Hello Cory,
Thank you for your response.
No, I'm ashamed to say, I didn't pass a boost::ref to the boost::thread.
And you sir, have hit a bull's eye.

Thanks again.
Dan
"Cory Nelson" <phrosty_at_[hidden]> wrote in message 
news:9b1d06140412051358291b9f4b_at_mail.gmail.com...
> 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

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