RFH: stale (f)lock in /proc/locks - process no longer exists
From: Philipp Hahn
Date: Wed Oct 14 2015 - 04:36:45 EST
Hi,
I have several shell scripts using "/usr/bin/flock -x
/run/lock/jenkins-ip.lock" to acquiring the exclusive lock. Today they
hang, while the lock is owned by a process which no longer exists:
# ls -i /run/lock/jenkins-ip.lock
766711440 /run/lock/jenkins-ip.lock
# grep 766711440 /proc/locks
1: FLOCK ADVISORY WRITE 1722 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 1725 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 20432 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 20618 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 16235 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 21757 00:12:766711440 0 EOF
1: -> FLOCK ADVISORY WRITE 29151 00:12:766711440 0 EOF
# lslocks -o COMMAND,PID,TYPE,MODE,PATH,BLOCKER
COMMAND PID TYPE MODE PATH BLOCKER
(unknown) 5852 FLOCK WRITE /run
cron 489 FLOCK WRITE /run/crond.pid
libvirtd 506 POSIX WRITE /run/libvirtd.pid
flock 29151 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
flock 21757 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
flock 16235 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
flock 20618 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
flock 20432 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
flock 1725 FLOCK WRITE* /run/lock/jenkins-ip.lock 1722
(unknown) 1722 FLOCK WRITE /run/lock
# ps 1722
PID TTY STAT TIME COMMAND
# uname -a
Linux test4 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u3
(2015-08-04) x86_64 GNU/Linux
1. How can this happen?
My understanding is, that all files are closed on process exit and
that all locks are released then. Did I miss something.
2. How can I release that lock?
Thanks in advance
Philipp
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