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Date: Sat, 21 Nov 2009 13:12:18 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Use of Dual Core causes random failures building OpenJDK
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On Nov 20 14:04, mike marchywka wrote:
> On 11/20/09, Christopher Faylor wrote:
> > On Fri, Nov 20, 2009 at 01:19:57PM -0500, mike marchywka wrote:
> >>On 11/20/09, Corinna Vinschen  wrote:
> >>> And given POSIX, if so, it would be an application bug if the application
> >>> doesn't care by itself to use setenv/getenv in a thread-safe manner.
> >>
> >>Why does the OS let this happen?  I thought windoze should avoid
> >>garbage.
> >
> > Er, I think you're a little confused about what we're talking about.  The
> > OS doesn't enforce thread safety.  There's really no way that it can.
> 
> We are talking about windoze env variables right? I did ask previously
> I thought.

We're only talking about Windows env variables if non-Cygwin processes
are involved.  As long as only Cygwin processes are involved in the
process, env variables are inherited via a Cygwin mechanism, not via
the Windows environment.

> The OS is the only place you can when the threads are in different
> processes unknown to each other. Or, can two different processes share
> the
> same thread?

No, never.  If there is a concurrency problem with the envionment, it's
between threads of the same process.  In that case, we can make getenv,
setenv and friends thread-safe, but it's still actually a problem of the
application, given that getenv, setenv and friends are not thread-safe
per POSIX.  See
http://www.opengroup.org/onlinepubs/9699919799/functions/setenv.html
http://www.opengroup.org/onlinepubs/9699919799/functions/getenv.html
http://www.opengroup.org/onlinepubs/9699919799/functions/unsetenv.html


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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