Date: Fri, 23 Mar 2012 16:18:43 GMT From: Christian Esken <christian.esken@trivago.com> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/166340: Process under FreeBSD 9.0 hangs in uninterruptable sleep with apparently no syscall (empty wchan) Message-ID: <201203231618.q2NGIhp4036716@red.freebsd.org> Resent-Message-ID: <201203231620.q2NGKBU9072860@freefall.freebsd.org>
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>Number: 166340 >Category: misc >Synopsis: Process under FreeBSD 9.0 hangs in uninterruptable sleep with apparently no syscall (empty wchan) >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Mar 23 16:20:11 UTC 2012 >Closed-Date: >Last-Modified: >Originator: Christian Esken >Release: FreeBSD 9.0 >Organization: >Environment: FreeBSD dev 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Thu Mar 1 17:17:19 CET 2012 root@dev:/usr/obj/usr/src/sys/GENERIC amd64 >Description: I have a process that sometimes goes into uninterruptable sleep under FreeBSD 9.0. "ps" shows the process is in "D" state and wchan is "-". The process works reliably under various other operating systems, including misc FreeBSD 8 versions. I presume it should never happen that a process is in uninterruptible sleep without showing the kernel call in wchan. What could be the reason, or how can I further tackle the situation? The nature of the process is a remote logger. It reads access logs from a pipe/STDIN (Apache httpd CustomLog) and sends them via TCP to a "scribed" logging server. More details can be found on Stackoverflow [1]. Below is some more information, like "procstat -k" and uname output. --------------- This is the result from "procstat -k" and "procstat -kk" # procstat -k 38013 PID TID COMM TDNAME KSTACK 38013 100817 serelog - mi_switch sleepq_check_timeout sleepq_timedwait_sig _sleep soreceive_generic kern_recvit recvit sys_recvfrom amd64_syscall Xfast_syscall # procstat -kk 38013 PID TID COMM TDNAME KSTACK 38013 100817 serelog - mi_switch+0x174 sleepq_check_timeout+0x80 sleepq_timedwait_sig+0x20 _sleep+0x1b1 soreceive_generic+0xf95 kern_recvit+0x205 recvit+0x21 sys_recvfrom+0x82 amd64_syscall+0x450 Xfast_syscall+0xf7 --------------- uname -a: FreeBSD dev 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Thu Mar 1 17:17:19 CET 2012 root@dev:/usr/obj/usr/src/sys/GENERIC amd64 There is no NFS involved on the system. Best regards, Christian [1] http://stackoverflow.com/questions/9786501/process-under-freebsd-9-0-hangs-in-uninterruptable-sleep-with-apparently-no-sysc >How-To-Repeat: I can reproduce the issue quickly by sending a lot of HTTP requests. The problem does not occur when tracing the process with truss. If not solvable by just the description, I will isolate a small test case from the full source code. >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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