From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id A2EE51F45A for ; Wed, 14 Aug 2019 10:43:48 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 76080120ADE; Wed, 14 Aug 2019 19:36:57 +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 0A0F9120ADA for ; Wed, 14 Aug 2019 19:36:54 +0900 (JST) Received: by filter0124p3las1.sendgrid.net with SMTP id filter0124p3las1-26440-5D53E449-3 2019-08-14 10:36:57.101867377 +0000 UTC m=+1612003.830643840 Received: from herokuapp.com (unknown [54.224.29.177]) by ismtpd0036p1iad1.sendgrid.net (SG) with ESMTP id kz5JnIzlTx-MZRg2dtjquQ for ; Wed, 14 Aug 2019 10:36:57.001 +0000 (UTC) Date: Wed, 14 Aug 2019 10:36:57 +0000 (UTC) From: deivid.rodriguez@riseup.net Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 69895 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 15912 X-Redmine-Issue-Author: deivid X-Redmine-Issue-Assignee: ko1 X-Redmine-Sender: deivid 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: =?us-ascii?Q?klzXTY0v3jOvaMSihdVenmzxCeXPrK4t1AV7GwiE8TiEbgy0GIEHNpMudRp6vc?= =?us-ascii?Q?aYF3Ec1dkPN2SACOfGIXQ2tXhCZtHbFE4flgaTy?= =?us-ascii?Q?Tcbcs+NQRGqSOm32Tti=2FYjwFEqyURxwYIsnBIL=2F?= =?us-ascii?Q?PUnCsCTqJ0ED5F4SiN29LbrmzwLid5KoBSKARHG?= =?us-ascii?Q?P0uN0u2t2YxCH9YDJH+h29FslNrJS7XILsA=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 94348 Subject: [ruby-core:94348] [Ruby master Feature#15912] Allow some reentrancy during TracePoint events 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="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #15912 has been updated by deivid (David Rodr=EDguez). The idea is to avoid recursive calls to the same event, but allow other kin= d of reentrancy. With a real script: ```ruby line_handler1 =3D TracePoint.trace(:line) do |tp| # L1 puts "Handler 1 starts (triggered from #{tp.path}:#{tp.lineno})" # L2 puts "Handler 1 ends (triggered from #{tp.path}:#{tp.lineno})" # L3 end # L4 # L5 = line_handler2 =3D TracePoint.trace(:line) do |tp| # L6 = puts "Handler 2 starts (triggered from #{tp.path}:#{tp.lineno})" # L7 puts "Handler 2 ends (triggered from #{tp.path}:#{tp.lineno})" # L8 end # L9 # L10 puts "I'm a line" # L11 ``` Current output is > Handler 1 starts (triggered by line tp.rb:6) > Handler 1 ends (triggered by line tp.rb:6) > Handler 2 starts (triggered by line tp.rb:11) > Handler 2 ends (triggered by line tp.rb:11) > Handler 1 starts (triggered by line tp.rb:11) > Handler 1 ends (triggered by line tp.rb:11) > I'm a line Proposed output would be > Handler 1 starts (triggered by line tp.rb:6) > Handler 1 ends (triggered by line tp.rb:6) > Handler 2 starts (triggered by line tp:11) > Handler 1 starts (triggered by line tp:7) > Handler 1 ends (triggered by line tp:7) > Handler 2 ends (triggered by line tp:11) > Handler 1 starts (triggered by line tp:8) > Handler 1 ends (triggered by line tp:8) > I'm a line By maybe the explicit solution you propose is better: allow every event to = be executed, also for code inside handlers, and let the user be in control = of avoiding potential infinite loops. ---------------------------------------- Feature #15912: Allow some reentrancy during TracePoint events https://bugs.ruby-lang.org/issues/15912#change-80751 * Author: deivid (David Rodr=EDguez) * Status: Assigned * Priority: Normal * Assignee: ko1 (Koichi Sasada) * Target version: = ---------------------------------------- I got a report in byebug about byebug being incompatible with zeitwerk. Thi= s one: https://github.com/deivid-rodriguez/byebug/issues/564. This is a pro= blem because zeitwerk is the default Rails code loader, and byebug is the d= efault Rails debugger. Both of these tools rely on the TracePoint API: * Byebug uses a bunch of TracePoint events to stop execution at certain poi= nts in your program. * Zeitwek uses `:class` events to be able to resolve some circular edge cas= es. I investigated the problem and I think the issue is that while stopped at t= he byebug prompt, we're actually in the middle of processing a TracePoint e= vent. That means that further TracePoint events triggered at the byebug's p= rompt will be ignored, because otherwise we could get into an infinite loop= where the handling of events would trigger more events that trigger themse= lves the execution of handlers again. I understand why the TracePoint API does this, but if we could allow some l= evel of reentrancy here, we could probably make these tools play nice toget= her. I figure if we kept a stack of TracePoint event handlers being run, an= d check that the current event type is not already in the stack, we would a= llow :class events to be triggered from :line events, and I think that woul= d allow Zeitwerk to work within byebug. What do you think about this, @ko1? -- = https://bugs.ruby-lang.org/ Unsubscribe: