>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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