Re: [Boost-build] CVS: boost/tools/build/v2/tools python.jam, 1.3 0, 1.31

From: David Abrahams (dave_at_[hidden])
Date: 2006-08-31 10:53:20

[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?

> and presumably the libc is multithreaded, so it conceivably the
> extension code could be run from a thread other than the main
> thread, 

No, Python controls all the calls it makes into the extension code and
ensures they're on the main thread.

> and call functions that adjust an errno it can't see.

Sorry, I don't follow.

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