Re: [Boost-build] Liking to pthreads

From: David Abrahams (dave_at_[hidden])
Date: 2006-09-09 12:34:30

Vladimir Prus <ghost_at_[hidden]> writes:

> On Thursday 07 September 2006 17:55, David Abrahams wrote:
>> Vladimir Prus <ghost_at_[hidden]> writes:
>> > On Monday 04 September 2006 16:34, David Abrahams wrote:
>> >> David Abrahams <dave_at_[hidden]> writes:
>> >> > [Taking this back to the boost.build list where it belongs]
>> >> >
>> >> > "MANSION, James, GBM" <James.MANSION_at_[hidden]> writes:
>> >> >>     # Even where Python itself uses pthreads, it never allows
>> >> >>     # extension modules to be entered concurrently (unless they
>> >> >>     # explicitly give up the interpreter lock).  Therefore,
>> >> >>     # extension modules don't need the efficiency overhead of
>> >> >>     # threadsafe code as produced by <threading>multi, and we
>> >> >>     # handle libpthread along with other libraries here.
>> >> >>
>> >> >> Is that absolutely right?  I mean, errno is sometimes different if
>> >> >> you are a single-threaded or multi-threaded build,
>> >> >
>> >> > In what way is errno different?
>> >>
>> >> James wasn't allowed to post to this list, and I quite impolitely
>> >> forwarded his comments here, for which I have apologized.  But he has
>> >> a point.  Suffice it to say that he convinced me <threading>multi is
>> >> required in general, even if on many systems it can probably be left
>> >> out for many programs.  Basically -mt has to be assumed to change the
>> >> ABI used by the standard library.
>> >
>> > The errno point is interesting.
>>
>> It's not just errno, as James pointed out to me in private email.  The
>> "usual implementation" of many standard libraries is engineered to
>> make errno work properly even if you link ST code with a MT code, but
>> that doesn't mean it's a workable practice in general.
>
> Can James post the email here?

No, James is not allowed to post to mailing lists.  However, you might
be able to get him to send you private email.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com