From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id 9E06C1F453 for ; Mon, 29 Oct 2018 01:13:54 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 695271214F4; Mon, 29 Oct 2018 10:13:52 +0900 (JST) Received: from o1678948x4.outbound-mail.sendgrid.net (o1678948x4.outbound-mail.sendgrid.net [167.89.48.4]) by neon.ruby-lang.org (Postfix) with ESMTPS id E3DB61214E3 for ; Mon, 29 Oct 2018 10:13:50 +0900 (JST) Received: by filter0081p3mdw1.sendgrid.net with SMTP id filter0081p3mdw1-994-5BD65ECA-27 2018-10-29 01:13:46.923427975 +0000 UTC m=+267293.854085864 Received: from herokuapp.com (ec2-54-80-22-45.compute-1.amazonaws.com [54.80.22.45]) by ismtpd0035p1mdw1.sendgrid.net (SG) with ESMTP id kTSHsyavTOa3clylOawVkw Mon, 29 Oct 2018 01:13:46.829 +0000 (UTC) Date: Mon, 29 Oct 2018 01:13:47 +0000 (UTC) From: nobu@ruby-lang.org To: ruby-core@ruby-lang.org Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 64994 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 15262 X-Redmine-Issue-Author: larskanis X-Redmine-Sender: nobu 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/Ymy4QrNMhiuLXJG8OTL2vJD1yS4aL/Z2CGld7FGDiyDGbuPLt2r/iS5FnOhPn5 H+2Cy8+dvCWN0efc4rmVHeR2yz50Ba+c+r6ZfjzdEHWcZ2P8KTCNX3mHtmP/Jex9R/IVfSCG+jKWmJ kZwfR9KyjB63Zp3lJTUYdS007Vy5N8nDKkBvhyYmj7PM0lDOuRBHOF6A/Q== X-ML-Name: ruby-core X-Mail-Count: 89610 Subject: [ruby-core:89610] [Ruby trunk Bug#15262] GCing of object in use 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 #15262 has been updated by nobu (Nobuyoshi Nakada). larskanis (Lars Kanis) wrote: > It does: `initialize` waits for all threads to have called `Adder#add` at the last line at `@qu.deq` . It only returns after this event. It waits just once. ---------------------------------------- Bug #15262: GCing of object in use https://bugs.ruby-lang.org/issues/15262#change-74649 * Author: larskanis (Lars Kanis) * Status: Feedback * Priority: Normal * Assignee: * Target version: * ruby -v: ruby 2.6.0dev (2018-10-27 trunk 65390) [x86_64-linux] * Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN ---------------------------------------- Given the following program: ```ruby require "weakref" Thread.abort_on_exception = true class Adder def self.start_adder(obj) obj.add end def initialize @qu = Queue.new @mutex = Mutex.new @mutex.lock begin @count = 10 @count.times do Thread.new(WeakRef.new(self), &self.class.method(:start_adder)) end ensure @mutex.unlock end @qu.deq end def add @mutex.lock begin @count-=1 if @count == 0 @qu.enq true elsif @count < 0 raise "shouldn't happen" end ensure @mutex.unlock end end end def test_adder 10.times.map do Thread.new do Adder.new end end.each(&:join) end 100.times do test_adder end ``` ## Expected behaviour: The program should simply execute without error. This is the case on JRuby but not on MRI. ## Actual behavior: The program stops with a probability of approximately 80% with the following error: ``` $ ruby -W2 adder-test.rb # terminated with exception (report_on_exception is true): Traceback (most recent call last): adder-test.rb:7:in `start_adder': Invalid Reference - probably recycled (WeakRef::RefError) Traceback (most recent call last): adder-test.rb:7:in `start_adder': Invalid Reference - probably recycled (WeakRef::RefError) ``` Although `start_adder` works with a `WeakRef`, the `Adder` object should still be GC marked, since `Adder.new` doesn't return before all calls to `start_adder` finished. I verified this on ruby-trunk, but get mostly the same behavior on all older MRI versions. -- https://bugs.ruby-lang.org/