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: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 324641F453 for ; Mon, 18 Feb 2019 21:50:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730984AbfBRVuJ (ORCPT ); Mon, 18 Feb 2019 16:50:09 -0500 Received: from elephants.elehost.com ([216.66.27.132]:37014 "EHLO elephants.elehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726955AbfBRVuI (ORCPT ); Mon, 18 Feb 2019 16:50:08 -0500 X-Virus-Scanned: amavisd-new at elehost.com Received: from gnash (CPE00fc8d49d843-CM00fc8d49d840.cpe.net.cable.rogers.com [99.229.179.249]) (authenticated bits=0) by elephants.elehost.com (8.15.2/8.15.2) with ESMTPSA id x1ILo1RZ083404 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 18 Feb 2019 16:50:02 -0500 (EST) (envelope-from rsbecker@nexbridge.com) From: "Randall S. Becker" To: "'Johannes Schindelin'" Cc: "'Junio C Hamano'" , "'Johannes Schindelin via GitGitGadget'" , , "'Max Kirillov'" References: <005401d4c4b3$147aa8c0$3d6ffa40$@nexbridge.com> <005901d4c4b9$3b9a2a60$b2ce7f20$@nexbridge.com> In-Reply-To: Subject: RE: [PATCH 0/1] Fix hang in t5562, introduced in v2.21.0-rc1 Date: Mon, 18 Feb 2019 16:49:54 -0500 Message-ID: <005c01d4c7d3$e5a3c850$b0eb58f0$@nexbridge.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Content-Language: en-ca Thread-Index: AQJRGauSxHI8crErjTmvoq3vRhvADwFUx24oAWoQp5kCOMthgQH1BI6TpLYM9LA= Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On February 18, 2019 15:41, Johannes Schindelin wrote: > To: Randall S. Becker > Cc: 'Junio C Hamano' ; 'Johannes Schindelin via > GitGitGadget' ; git@vger.kernel.org; 'Max Kirillov' > > Subject: RE: [PATCH 0/1] Fix hang in t5562, introduced in v2.21.0-rc1 > > Hi Randall, > > On Thu, 14 Feb 2019, Randall S. Becker wrote: > > > On February 14, 2019 17:39, Junio C Hamano wrote: > > > To: Randall S. Becker > > > Cc: 'Johannes Schindelin via GitGitGadget' ; > > > git@vger.kernel.org; 'Max Kirillov' > > > Subject: Re: [PATCH 0/1] Fix hang in t5562, introduced in > > > v2.21.0-rc1 > > > > > > "Randall S. Becker" writes: > > > > > > > Unfortunately, subtest 13 still hangs on NonStop, even with this > > > > patch, so our Pipeline still hangs. I'm glad it's better on Azure, > > > > but I don't think this actually addresses the root cause of the hang. > > > > > > Sigh. > > > > > > > possible this is not the test that is failing, but actually the > > > > git-http-backend? The code is not in a loop, if that helps. It is > > > > not consuming any significant cycles. I don't know that part of > > > > the code at all, sadly. The code is here: > > > > > > > > * in the operating system from here up * > > > > cleanup_children + 0x5D0 (UCr) > > > > cleanup_children_on_exit + 0x70 (UCr) > > > > git_atexit_dispatch + 0x200 (UCr) > > > > __process_atexit_functions + 0xA0 (DLL zcredll) > > > > CRE_TERMINATOR_ + 0xB50 (DLL zcredll) > > > > exit + 0x2A0 (DLL zcrtldll) > > > > die_webcgi + 0x240 (UCr) > > > > die_errno + 0x360 (UCr) > > > > write_or_die + 0x1C0 (UCr) > > > > end_headers + 0x1A0 (UCr) > > > > die_webcgi + 0x220 (UCr) > > > > die + 0x320 (UCr) > > > > inflate_request + 0x520 (UCr) > > > > run_service + 0xC20 (UCr) > > > > service_rpc + 0x530 (UCr) > > > > cmd_main + 0xD00 (UCr) > > > > main + 0x190 (UCr) > > > > > > > > Best guess is that a signal (SIGCHLD?) is possibly getting eaten > > > > or neglected somewhere between the test, perl, and git-http-backend. > > > > > > So we are trying to die(), which actually happens in die_webcgi(), > > > and > > then try > > > to write some message _but_ notice an error inside > > > write_or_dir() and try to exit because we do not want to recurse > > > forever trying to die, giving a message to say how/why we died, and > > > die because failing to give that message, forever. > > > > > > But in our attempt to exit(), we try to "cleanup children" and that > > > is > > what gets > > > stuck. > > > > > > One big difference before and after the /dev/zero change is that the > > process > > > is now on a downstream of the pipe. If we prepare a large file with > > > a > > finite > > > size full of NULs and replace /dev/null with it, instead of feeding > > > NULs > > from > > > the pipe, would it change the equation? > > > > Doubtful. The processes are still around, and are waiting on read but > > not actively reading (CPU time is not going up, so we're not reading > > an infinite stream). To me, this is a pipe situation where there is > > simply nothing waiting on the pipe (maybe a flush missing?). I'm > > grasping are straws without knowing the actual process architecture of the > test to debug it. > > So could you try with this patch? > > -- snipsnap -- > diff --git a/http-backend.c b/http-backend.c index d5cea0329a..7c1b4a2555 > 100644 > --- a/http-backend.c > +++ b/http-backend.c > @@ -427,6 +427,7 @@ static void inflate_request(const char *prog_name, > int out, int buffer_input, ss > > done: > git_inflate_end(&stream); > + close(0); > close(out); > free(full_request); > } Based on d62dad7a7d (v2.21.0-rc0) undoing all of the fixes, this change on its own makes no difference to the hang situation - it is still there as it was when originally reported. Using POSIX::_exit does not change the outcome of the test either on its own or in conjunction with this fix.