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=-3.3 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 6D3771F453 for ; Sun, 28 Oct 2018 11:52:54 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 8DC9B121435; Sun, 28 Oct 2018 20:52:52 +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 79E97121431 for ; Sun, 28 Oct 2018 20:52:49 +0900 (JST) Received: by filter0145p3las1.sendgrid.net with SMTP id filter0145p3las1-18654-5BD5A30E-C 2018-10-28 11:52:46.329072335 +0000 UTC m=+733714.012892429 Received: from herokuapp.com (ec2-54-166-181-133.compute-1.amazonaws.com [54.166.181.133]) by ismtpd0031p1mdw1.sendgrid.net (SG) with ESMTP id WUlld7xDRnGxw71_efMbgA Sun, 28 Oct 2018 11:52:46.143 +0000 (UTC) Date: Sun, 28 Oct 2018 11:52:46 +0000 (UTC) From: lars@greiz-reinsdorf.de To: ruby-core@ruby-lang.org Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 64990 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 15262 X-Redmine-Issue-Author: larskanis X-Redmine-Sender: larskanis 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/Ymy4QrNMhiuLXJG8OTL2vJD1yS5p5wXkfffrhT0kp+J4XLzDcg0CucO5nnZzDk nbV+LJ5wk1oafftMPa4hbqDs+HnVAT13JU/iRYGAgIB/kZmM2ZHoADT+dSbCaHMngPcUVpy9qZB5Xb uqG6BUGQYBiqaA/qcV3aJ5HeGqzyAxYKbg/DEEGiHJyabnLX8HNtW8LOmQ== X-ML-Name: ruby-core X-Mail-Count: 89606 Subject: [ruby-core:89606] [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 larskanis (Lars Kanis). Thanks @nobu for looking at the issue! > This method doesn't wait these threads which run start_adder. 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. ---------------------------------------- Bug #15262: GCing of object in use https://bugs.ruby-lang.org/issues/15262#change-74643 * 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/