From: Jim Jagielski <jim@jaguNET.com>
Message-Id: <199702121052.FAA29371@shado.jaguNET.com>
Subject: Re: [PATCH] lingering_close performance improvement
To: new-httpd@hyperreal.com
Date: Wed, 12 Feb 1997 05:52:26 -0500 (EST)
In-Reply-To: <Pine.BSI.3.91.970212092652.5708A-100000@hume.esi.co.uk> from
 "David Robinson" at Feb 12, 97 09:42:08 am
Content-Type: text
Sender: new-httpd-owner@apache.org
Precedence: bulk
Reply-To: new-httpd@hyperreal.com

David Robinson wrote:
> 
> On Tue, 11 Feb 1997, Dean Gaudet wrote:
> 
> > You can open a single socketpair() before forking that all children use to
> > send to the parent.  If the buffer isn't full (heh) then a write() of a
> > "small size" is atomic. 
> > 
> > Anyone know if POSIX promises that behaviour?  We actually already rely on
> > it -- all our log code assumes that write() for a "small size" is atomic
> > (and that the OS implements O_APPEND atomically as well, and that the
> > underlying fs allows the atomicity to work... i.e. not NFS). 
> 
> Yes...
> When writing to a pipe or FIFO (N.B. _not_ a socket), write requests of 
> PIPE_BUF or less are guaranteed to be atomic; i.e. will not be interleved 
> with data from other processes doing writes on the same pipe. PIPE_BUF is 
> usually defined in limits.h; the Solaris 2.5.1 file has PIPE_BUF of 5120 
> and implies that the Posix required minimum value is 512.
> 

Hmmmm wonder if I can consider this the "double checking" mentioned
in my previous Email :)

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      Jim Jagielski            |       jaguNET Access Services
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