From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-3.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,RP_MATCHES_RCVD,SPF_PASS,T_DKIM_INVALID shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id CCC33202A5 for ; Mon, 25 Sep 2017 12:41:49 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id AFADD1209E7; Mon, 25 Sep 2017 21:41:47 +0900 (JST) Received: from o1678916x28.outbound-mail.sendgrid.net (o1678916x28.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id 37BD21209E2 for ; Mon, 25 Sep 2017 21:41:46 +0900 (JST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=sendgrid.me; h=from:to:references:subject:mime-version:content-type:content-transfer-encoding:list-id; s=smtpapi; bh=IizF8Xwos03ZgBfuGyMfxAZ/FOs=; b=UKBKYlvVJ42HENeVSq qP8sGcr2PaWXQrbAKtQMhowDROCfYWJAo71Npx8z/hnf0ScHotHaoIb3pd9YA02w BGU9AjDMcRZyW3r8gsEL2BEeFsdoCKe+tPBI8mIRw5il+tKs1f3eeYCrOhcL+lao EQnTRDMfCHBXfzMbGEUsbBJy8= Received: by filter0004p3mdw1.sendgrid.net with SMTP id filter0004p3mdw1-28141-59C8F987-36 2017-09-25 12:41:43.733056274 +0000 UTC Received: from herokuapp.com (ec2-54-160-132-132.compute-1.amazonaws.com [54.160.132.132]) by ismtpd0007p1iad1.sendgrid.net (SG) with ESMTP id KpfnZHWvQc2XMDnQmZ7vgA Mon, 25 Sep 2017 12:41:43.628 +0000 (UTC) Date: Mon, 25 Sep 2017 12:41:43 +0000 (UTC) From: shyouhei@ruby-lang.org To: ruby-core@ruby-lang.org Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 58095 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 13821 X-Redmine-Issue-Author: cremes X-Redmine-Issue-Assignee: ko1 X-Redmine-Sender: shyouhei X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-SG-EID: ync6xU2WACa70kv/Ymy4QrNMhiuLXJG8OTL2vJD1yS7vcbLN5RB7rvhXtWegUZ7OQXxsMAaRTVFSNl I8g3yuff9uw5CJT1kcVmPJ0QPhiDBNDkYuIZkeCdW3CgimeGCPxQJHlW41NFI9nG63Olez3Y2OnxqW zZSaf3ykcLjE/PYfTDy0Zx9QvRTPnbnBIg7XTXEBUQVxpJ1lnX1v63z93w== X-ML-Name: ruby-core X-Mail-Count: 82994 Subject: [ruby-core:82994] [Ruby trunk Feature#13821][Assigned] Allow fibers to be resumed across threads X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #13821 has been updated by shyouhei (Shyouhei Urabe). Status changed from Open to Assigned Assignee set to ko1 (Koichi Sasada) In the today's developer meeting Ko1 said that migrating fibers across threads is currently not possible. I think he would like to explain why, so let me assign this issue to him. ---------------------------------------- Feature #13821: Allow fibers to be resumed across threads https://bugs.ruby-lang.org/issues/13821#change-66902 * Author: cremes (Chuck Remes) * Status: Assigned * Priority: Normal * Assignee: ko1 (Koichi Sasada) * Target version: ---------------------------------------- Given a Fiber created in ThreadA, Ruby 2.4.1 (and earlier releases) raise a FiberError if the fiber is resumed in ThreadB or any other thread other than the one that created the original Fiber. Sample code attached to demonstrate problem. If Fibers are truly encapsulating all of the data for the continuation, we should be allowed to move them between Threads and resume their operation. Why? One use-case is to support the async-await asynchronous programming model. In that model, a method marked async runs *synchronously* until the #await method is encountered. At that point the method is suspended and control is returned to the caller. When the #await method completes (asynchronously) then it may resume the suspended method and continue. The only way to capture this program state, suspend and resume, is via a Fiber. example: ``` class Wait include AsyncAwait def dofirst async do puts 'Synchronously print dofirst.' result = await { dosecond } puts 'dosecond is complete' result end end def dosecond async do puts 'Synchronously print dosecond from async task.' slept = await { sleep 3 } puts 'Sleep complete' slept end end def run task = dofirst puts 'Received task' p AsyncAwait::Task.await(task) end end Wait.new.run ``` ``` # Expected output: # Synchronous print dofirst. # Received task # Synchronously print dosecond from async task. # Sleep complete # dosecond is complete # 3 ``` Right now the best way to accomplish suspension of the #dofirst and #dosecond commands and allow them to run asynchronously is by passing those blocks to *another thread* (other than the callers thread) so they can be encapsulated in a new Fiber and then yielded. When it's time to resume after #await completes, that other thread must lookup the fiber and resume it. This is lots of extra code and logic to make sure that fibers are only resumed on the threads that created them. Allowing Fibers to migrate between threads would eliminate this problem. ---Files-------------------------------- fiber_across_threads.rb (377 Bytes) wait.rb (728 Bytes) -- https://bugs.ruby-lang.org/