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=-3.6 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 C54D01F453 for ; Tue, 30 Oct 2018 01:34:55 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id A01EC12168F; Tue, 30 Oct 2018 10:34:54 +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 E360E12168E for ; Tue, 30 Oct 2018 10:34:51 +0900 (JST) Received: by filter0075p3mdw1.sendgrid.net with SMTP id filter0075p3mdw1-20358-5BD7B538-22 2018-10-30 01:34:48.896869685 +0000 UTC m=+363972.493183807 Received: from herokuapp.com (ec2-54-166-16-44.compute-1.amazonaws.com [54.166.16.44]) by ismtpd0010p1iad1.sendgrid.net (SG) with ESMTP id iiXwixIkT7m3Jm66q1QYfQ Tue, 30 Oct 2018 01:34:48.859 +0000 (UTC) Date: Tue, 30 Oct 2018 01:34:49 +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: 65010 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/Ymy4QrNMhiuLXJG8OTL2vJD1yS6Wi5ov8tpD3WsRoxDATWlnOnAgDtVBz7cXj1 fkhdEAgPzSFs31golRltCzgB2nLu0hgsuopklWeE0NvkuJRIKbii3LtPhFiGXzvXvvwPQ2UHA+gjuS oiumnLchYtYF1x+yJoQuMGWfSQqZ2NKf83fGeDIYDqeqD45KkZQd1KMraw== X-ML-Name: ruby-core X-Mail-Count: 89625 Subject: [ruby-core:89625] [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 waits just once. > > Yes, but the one event is sent after all 10 threads have been called, so that `@count` is decremented to 0. Why do you think so? ---------------------------------------- Bug #15262: GCing of object in use https://bugs.ruby-lang.org/issues/15262#change-74663 * 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. ---Files-------------------------------- adder-test2.rb (476 Bytes) -- https://bugs.ruby-lang.org/