From owner-freebsd-bugs@freebsd.org Tue Nov 29 09:28:18 2016 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CDAEEC59819 for ; Tue, 29 Nov 2016 09:28:18 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BD4001589 for ; Tue, 29 Nov 2016 09:28:18 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id uAT9SI5J028829 for ; Tue, 29 Nov 2016 09:28:18 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 214923] kqueue hangs with busy loop Date: Tue, 29 Nov 2016 09:28:18 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: kib@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Nov 2016 09:28:18 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D214923 Konstantin Belousov changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kib@FreeBSD.org --- Comment #1 from Konstantin Belousov --- (In reply to yjh0502 from comment #0) I do not see a clean indicator that the process 'spins on the kqueue syscal= l'.=20 The wait channel demonstrates that the process waits for some event subsyst= em mutex (the star before the name), but due to the truncated output, I am not sure which mutex is it. It could kqueue lock, or kqueue global lock, for instance. That said, WCPU 100% indicates that there is some other thread in the proce= ss which consumes cycles, which is consistent with the report of four threads = in the process. >From that data, I am not even convinced that this is a kernel bug and not s= ome application issue. For very beginning, look at the kernel backtraces of all threads in your process with procstat -kk. Find and backtrace the lock own= er of a kqueue lock. All that assuming that you believe that the issue is a kernel problem. Otherwise, and I would start with that route, would I debu= g it myself, is to look at the app and see what it is doing (wrong). --=20 You are receiving this mail because: You are the assignee for the bug.=