From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from endymion.arp.harvard.edu (endymion.arp.harvard.edu [140.247.179.94]) by sourceware.org (Postfix) with ESMTPS id 47E68385E009 for ; Thu, 26 Mar 2020 17:00:22 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 47E68385E009 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=huarp.harvard.edu Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=allen@huarp.harvard.edu Received: from [192.168.7.24] (pool-74-104-152-231.bstnma.fios.verizon.net [74.104.152.231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by endymion.arp.harvard.edu (Postfix) with ESMTPSA id BD9AF6C0946; Thu, 26 Mar 2020 13:00:21 -0400 (EDT) Subject: Re: Sv: Named pipes and multiple writers To: Ken Brown , cygwin References: <1b1401d60296$2769e690$763db3b0$@gmail.com> <716e2076-f607-454e-2723-937c3959e2a3@cornell.edu> <18be01d602ab$0bbfca30$233f5e90$@gmail.com> <35b43b59-6410-f21f-710c-385e39cbae0b@cornell.edu> <18b661e1-e8f5-bcc6-0211-e39c383c1580@cornell.edu> <73d9c583-acf7-08bb-c034-e30b29898ca0@huarp.harvard.edu> <5a308064-405a-a231-dee4-56d10d7cd7c9@cornell.edu> From: Norton Allen Message-ID: Date: Thu, 26 Mar 2020 13:00:20 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <5a308064-405a-a231-dee4-56d10d7cd7c9@cornell.edu> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Mar 2020 17:00:23 -0000 On 3/26/2020 12:44 PM, Ken Brown via Cygwin wrote: > On 3/26/2020 12:03 PM, Norton Allen wrote: >> On 3/26/2020 11:11 AM, Ken Brown via Cygwin wrote: >>> >>> BTW, I've been working on adding support for multiple readers.  I >>> expect to have a first cut ready within a week or two.  Would you >>> have any use for that?  If so, I could revive the topic/fifo branch >>> and push my patches there for you to test. >>> >> >> Ken, what are the semantics for multiple readers? Do all readers see >> the same data,  or is it first come first served or something else? > > It's first come, first served.  If two readers attempt to read > simultaneously, it's possible that one will get some of the available > input and the other will get some more. > > The only use case for multiple readers that I've come across of is > Midnight Commander running under tcsh.  I didn't dig into the code > enough to know why they do it, or why only under tcsh.  See > > https://sourceware.org/pipermail/cygwin/2019-December/243317.html > > and > > https://cygwin.com/pipermail/cygwin-apps/2019-December/039777.html > > That's what got me interested in this.  It would be nice to know if > there are other use cases. > I suppose it could be used as a simple approach to deploying jobs to worker processes, provided a process could guarantee that it received enough information to define a job and not more than one. I guess if the job definition were fixed length that could work.