From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by sourceware.org (Postfix) with ESMTPS id 28F613858C2C for ; Fri, 15 Apr 2022 18:09:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 28F613858C2C Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=ispras.ru Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=ispras.ru Received: from mail.ispras.ru (unknown [83.149.199.84]) by mail.ispras.ru (Postfix) with ESMTPSA id 2C0F640D403D for ; Fri, 15 Apr 2022 18:09:05 +0000 (UTC) MIME-Version: 1.0 Date: Fri, 15 Apr 2022 21:09:05 +0300 From: Alexey Izbyshev To: cygwin@cygwin.com Subject: Deadlock when pressing Ctrl-C at startup of a native console application User-Agent: Roundcube Webmail/1.4.4 Message-ID: <355a1f23bf39b0670110a840075224a2@ispras.ru> X-Sender: izbyshev@ispras.ru Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.0 required=5.0 tests=BAYES_00, DOS_RCVD_IP_TWICE_B, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Apr 2022 18:09:11 -0000 Hi, I've discovered that pressing Ctrl-C in a Cygwin ssh session running the following command can cause a deadlock: $ while python -c ''; do :; done The exact native application doesn't matter here, e.g. "ping -n 1 localhost >/dev/null" instead of "python -c ''" also "works". The deadlock is most easily triggered when CPU is fully loaded. It takes no more than 20 tries on my machine to hit it (and when I first saw it, it was on the first try). When the deadlock is triggered, there are conhost.exe and cygwin-console-helper.exe processes, but there is no python. The exact process tree varies depending on Cygwin version. With the vanilla 3.3.4 (the root is bash spawned by sshd): bash---bash-+-conhost.exe `-cygwin-console-helper.exe With 20220301 snapshot (https://cygwin.com/snapshots/x86/cygwin1-20220301.dll.xz), I get one of the two following trees with an extra conhost.exe process: bash---bash-+-conhost.exe |-conhost.exe `-cygwin-console-helper.exe or bash---bash-+-conhost.exe | `-cygwin-console-helper.exe `-conhost.exe I was testing with 32-bit Cygwin on x64 Windows 10 21H2. Thanks, Alexey