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From: Heribert Dahms <heribert_dahms AT icon-scm DOT com>
To: "'Robert Collins'" <robert DOT collins AT itdomain DOT com DOT au>, cygwin AT cygwin DOT com
Subject: RE: pthread: thread switching bug?
Date: Sat, 3 Nov 2001 00:50:06 +0100 
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Hi Rob,

I'd expect write() to be atomic, if "small" enough, but not print() or
fprintf()!

I once more cite APUE
(Richard W. Steven's Advanced Programming in the UNIX Environment),
chapter 10.6 Reentrant Functions:
"Most implementations of the standard I/O library
use global data structures in a nonreentrant way"
right under figure 10.3:
Reentrant functions that may be called from a signal handler.

Methinks this precaution applies also to MT!


Bye, Heribert (heribert_dahms AT icon-scm DOT com)

> -----Original Message-----
> From:	Robert Collins [SMTP:robert DOT collins AT itdomain DOT com DOT au]
> Sent:	Thursday, November 01, 2001 03:38
> To:	cygwin AT cygwin DOT com
> Subject:	RE: pthread: thread switching bug?
> 
> > -----Original Message-----
> > From: Christopher Faylor [mailto:cgf AT redhat DOT com]
> > >Thanks for the testing, you've shown that there is non 
> > thread safe code,
> > >probably in the fhandler_consoler in cygwin, or possibly in the MS
> > >Windows console code. Right now we don't know which.
> > 
> > I'm still not sure why this is a cygwin bug.  Is there some 
> > requirement
> > that writes to the console be atomic?  Your (Robert's) original email
> > indicated that the Opengroup spec didn't have this as a requirement.
> 
> It's non expected behaviour at the least. At worst it could be a symptom
> of something more serious that is faulty. I intend to analyse it at some
> point. 
> 
> The Opengroup spec for printf doesn't document any thead safety needs,
> but, one would expect fprintf to a file to be atomic regardless of the
> actual file... There are separate thread considerations elsewhere in
> that tome, but I don't have time to dig them up right now.
> 
> Rob
> 
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