From owner-sc22wg5@open-std.org Wed Oct 21 13:50:48 2009 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 65426C178E4; Wed, 21 Oct 2009 13:50:48 +0200 (CET DST) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from mail1.cray.com (mail1.cray.com [136.162.62.100]) by www2.open-std.org (Postfix) with ESMTP id 7A092C178E3 for ; Wed, 21 Oct 2009 13:50:46 +0200 (CET DST) Received: from beaver.us.cray.com (beaver.us.cray.com [172.30.74.51]) by mail1.cray.com (8.13.6/8.13.3/gw-5323) with ESMTP id n9LBoiUI017848 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); Wed, 21 Oct 2009 06:50:44 -0500 (CDT) Received: from cfexcas02.americas.cray.com (cfexcas02-2.us.cray.com [172.30.74.228]) by beaver.us.cray.com (8.13.8/8.13.3/hub-5273) with ESMTP id n9LBohN8016522; Wed, 21 Oct 2009 06:50:43 -0500 Received: from bill-longs-macbook-pro.local (192.168.239.2) by cfexcas02.americas.cray.com (172.30.74.226) with Microsoft SMTP Server (TLS) id 8.1.393.1; Wed, 21 Oct 2009 06:50:42 -0500 Message-ID: <4ADEF5A8.4080703@cray.com> Date: Wed, 21 Oct 2009 06:51:04 -0500 From: Bill Long Reply-To: Organization: Cray Inc. User-Agent: Thunderbird 2.0.0.23 (Macintosh/20090812) MIME-Version: 1.0 To: fortran standards email list for J3 Cc: SC22WG5 Subject: Re: (j3.2006) (SC22WG5.4096) [ukfortran] Standard intrinsics andcoarrays References: <20091020111544.C0F5CC178E3@www2.open-std.org> <4ADDC3E1.4030007@cray.com> <20091021055318.EF688C178E3@www2.open-std.org> In-Reply-To: <20091021055318.EF688C178E3@www2.open-std.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Cray-VirusStatus: clean Sender: owner-sc22wg5@open-std.org Precedence: bulk Malcolm Cohen wrote: > Bill Long wrote: >> If an environment variable is never changed during execution of the program, >> then I don't see an issue with GET_ENVIRONMENT_VARIABLE either. > > Why would we expect the same environment variables to exist for the whole > program? I would expect that the program launching mechanism would establish the same environment for each image. However, as Nick's second version proposal suggests, this might not be true for some cases. On a loosely-connected cluster, each image is going to have its own > set of environment variables and some could well be different (like HOST for > example). > > We probably ought to say that environment variables are per-image. I think this would be at least as bad - probably worse. It would imply to the user that each image could independently set the value of an environment variable, which would be impossible on most systems. The "processor-dependent" approach is better. A user who wants portable code would call GET_ENVIRONMENT_VARIABLE only on image 1. It might be worth adding that suggestion to Nick's NOTE. Cheers, Bill The current > text certainly implies that GET_ENVIRONMENT_VARIABLE will return the same value > on each image, and that is surely a limitation we don't want to apply. > > Cheers, -- Bill Long longb@cray.com Fortran Technical Support & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120