Re: Thread destruction in boost

From: bill_kempf (williamkempf_at_[hidden])
Date: 2002-05-15 16:06:48

--- In Boost-Users_at_y..., "giltayar" <gil_at_t...> wrote:
> 1. On the multi-join/default constructor issue:
> 
> Hmmm... hadn't noticed the default ctor. The multi-join issue is a 
> valid one. How I would solve it is for the dtor to "know" whether a 
> join was called (using a private member), i.e. whether thread is 
> alive or not, and thus know whether to join() it.

Yes, it's possible, but the semantics result in something that's at 
least a little surprising to some, and possibly not valid for others.

> 2. On the "leak":
> 
> How about this code:
> 
> void Foo (FooType& x)
> {
>   MyFunction f(x);
>   boost:thread t(f);
>   // continue processing...
>   if (error-occured-during-processing)
>      throw std::exception("ouch");
>   // continue processing...
>   t.join();
> }
> 
> As a user of RIIA (resource-initialization-is-acquisition), this 
code 
> would have looked apppropriate and OK. But it is wrong, because the 
> thread may be accessing f, which will be out of scope in case the 
> exception was thrown! To fix it, one should do...

No, it won't access an out of scope f.  Why?  Because the thread 
never accesses f at all.  It uses a *copy* of f, whose lifetime will 
remain valid.  In any case, you're describing a different problem 
from a "thread leak", and the above code simply won't "leak".
 
> P.S. Am I re-hashing previous conversations? In this mailing list 
> there is no searching capabilities, so I don't know.

Sure there's searching.  Are you using the YahooGroups web interface?

Bill Kempf