From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB9F6C433DF for ; Thu, 4 Jun 2020 12:41:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 807102063A for ; Thu, 4 Jun 2020 12:41:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O7hERcHH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 807102063A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40320 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jgpBi-0002Ra-O3 for qemu-devel@archiver.kernel.org; Thu, 04 Jun 2020 08:41:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53008) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jgp9i-00089O-SG for qemu-devel@nongnu.org; Thu, 04 Jun 2020 08:39:34 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51946 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jgp9g-0001iH-Rv for qemu-devel@nongnu.org; Thu, 04 Jun 2020 08:39:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591274371; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7jvOOxTK8bCohiwVvxochZNE0up0QJofGpeLnUE403s=; b=O7hERcHHfBj0vszre5ryRXNlK7PxsnLx3LJvEjtcY4vB93q/3ilUaQ2YlkozXYrqcFbyF2 uCTFvR+bgu5OcXzMimNHDmr0V0l1FFNPRmUrsqob0BCNrglFf3qsNJFJt4EtK8wvmfHMVY 2Xfw5ybjVSKjc9MWyEmZL3lQvr5eYFw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-168-pQva1r9vMXm8GPijaJh2Lw-1; Thu, 04 Jun 2020 08:39:27 -0400 X-MC-Unique: pQva1r9vMXm8GPijaJh2Lw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8D57AEC1AA for ; Thu, 4 Jun 2020 12:39:26 +0000 (UTC) Received: from linux.fritz.box (ovpn-112-65.ams2.redhat.com [10.36.112.65]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1AE727BA00; Thu, 4 Jun 2020 12:39:17 +0000 (UTC) Date: Thu, 4 Jun 2020 14:39:16 +0200 From: Kevin Wolf To: John Snow Subject: Re: [PATCH v2 1/1] python/machine.py: refactor shutdown Message-ID: <20200604123916.GF4512@linux.fritz.box> References: <20200602194844.15258-1-jsnow@redhat.com> <20200602194844.15258-2-jsnow@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200602194844.15258-2-jsnow@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/04 01:12:15 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Cleber Rosa , philmd@redhat.com, qemu-devel@nongnu.org, Eduardo Habkost , Markus Armbruster Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 02.06.2020 um 21:48 hat John Snow geschrieben: > This is done primarily to avoid the 'bare except' pattern, which > suppresses ALL exceptions and not just ones that we are anticipating to > see. > > Replace this with a pattern that isolates the different kind of shutdown > paradigms and a new fallback shutdown handler that gracefully attempts > one before the other. > > Move all of the post-shutdown code into _post_shutdown, and adjust the > main shutdown() function to ALWAYS call the post_shutdown logic no > matter what kind of error we encountered: An expected one (subprocess > wait timeout) or an unexpected one (Everything else). > > In cases where we encounter an expected error in the graceful shutdown > timeout, we will not re-raise an exception above shutdown(). Otherwise, > after post_shutdown cleanup, we will. > > I anticipate that this WILL lead to additional bug reports filed against > this module, but that is unfortunately somewhat the point: This code > shouldn't be hiding failures that exist elsewhere within the python > code. > > Signed-off-by: John Snow > --- > python/qemu/machine.py | 93 +++++++++++++++++++++++++++++------------- > 1 file changed, 65 insertions(+), 28 deletions(-) > > diff --git a/python/qemu/machine.py b/python/qemu/machine.py > index 041c615052e..a2abd2c35e3 100644 > --- a/python/qemu/machine.py > +++ b/python/qemu/machine.py > @@ -283,6 +283,8 @@ def _post_launch(self): > self._qmp.accept() > > def _post_shutdown(self): > + self._load_io_log() > + > if self._qemu_log_file is not None: > self._qemu_log_file.close() > self._qemu_log_file = None > @@ -296,6 +298,17 @@ def _post_shutdown(self): > while len(self._remove_files) > 0: > self._remove_if_exists(self._remove_files.pop()) > > + exitcode = self.exitcode() > + if exitcode is not None and exitcode < 0: > + msg = 'qemu received signal %i; command: "%s"' > + if self._qemu_full_args: > + command = ' '.join(self._qemu_full_args) > + else: > + command = '' > + LOG.warning(msg, -int(exitcode), command) > + > + self._launched = False It would have been a little easier to review if this code motion to _post_shutdown() were a separate patch. It looks mostly independent of the other changes. The big change here is that we now log warnings for exit due to a signal for QEMUMachine.wait(), too. I assume this is okay. > def launch(self): > """ > Launch the VM and make sure we cleanup and expose the > @@ -344,12 +357,53 @@ def wait(self): > self._popen.wait() > if self._qmp: > self._qmp.close() > - self._load_io_log() > self._post_shutdown() > > - def shutdown(self, has_quit=False, hard=False): > + def _hard_shutdown(self) -> None: > """ > - Terminate the VM and clean up > + Kill the VM if it is running. > + """ > + if not self.is_running(): > + return > + > + self._popen.kill() > + self._popen.wait(timeout=60) > + > + def _soft_shutdown(self, has_quit: bool = False, timeout: int = 3) -> None: > + """ > + Attempt to shutdown the VM gracefully if it is running. > + > + :param has_quit: When True, don't attempt to issue 'quit' QMP command > + :param timeout: Timeout for graceful shutdown. Default 3 seconds. > + """ > + if not self.is_running(): > + return > + > + if self._qmp is not None: > + if not has_quit: > + self._qmp.cmd('quit') > + self._qmp.close() > + > + self._popen.wait(timeout=timeout) > + > + def _do_shutdown(self, has_quit: bool = False, timeout: int = 3) -> None: > + """ > + Attempt to shutdown the VM gracefully; fallback to a hard shutdown. > + > + :param has_quit: When True, don't attempt to issue 'quit' QMP command > + :param timeout: Timeout for graceful shutdown. Default 3 seconds. > + """ > + try: > + self._soft_shutdown(has_quit, timeout) > + except subprocess.TimeoutExpired: > + self._hard_shutdown() > + except: > + self._hard_shutdown() > + raise > + > + def shutdown(self, has_quit: bool = False, hard: bool = False) -> None: > + """ > + Terminate the VM (gracefully if possible) and perform cleanup. > """ > # If we keep the console socket open, we may deadlock waiting > # for QEMU to exit, while QEMU is waiting for the socket to > @@ -358,35 +412,18 @@ def shutdown(self, has_quit=False, hard=False): > self._console_socket.close() > self._console_socket = None > > - if self.is_running(): > + try: > if hard: > - self._popen.kill() > - elif self._qmp: > - try: > - if not has_quit: > - self._qmp.cmd('quit') > - self._qmp.close() > - self._popen.wait(timeout=3) > - except: > - self._popen.kill() > - self._popen.wait() > - > - self._load_io_log() > - self._post_shutdown() > - > - exitcode = self.exitcode() > - if exitcode is not None and exitcode < 0 and \ > - not (exitcode == -9 and hard): The condition in the second line went away without a replacement. This means that previously, intentionally killing a VM with hard=True would not log a warning (which makes sense to me), but now it does. On the other hand, I couldn't find a single user of hard=True or the kill() method in the whole tree. So I guess it doesn't matter anyway? > - msg = 'qemu received signal %i: %s' > - if self._qemu_full_args: > - command = ' '.join(self._qemu_full_args) > + self._hard_shutdown() > else: > - command = '' > - LOG.warning(msg, -int(exitcode), command) > - > - self._launched = False > + self._do_shutdown(has_quit) > + finally: > + self._post_shutdown() > > def kill(self): > + """ > + Terminate the VM forcefully and perform cleanup. > + """ > self.shutdown(hard=True) > > def set_qmp_monitor(self, enabled=True): In the end, while the new behaviour is a bit different in details, it's not unreasonable, and if it does cause any problems, we can still change it back. Reviewed-by: Kevin Wolf