clobbering stale lock file

keat63

March 15, 2018 03:22

Could anyone help decipher this please. I've seen the same (or similar worded) error on two mornings.


/usr/local/cpanel/logs/error_log:
[2018-03-15 05:13:06 +0000] warn [tailwatchd] [17183] UID 0 clobbering stale lock file "??/var/run/chkservd.checking.lock"?" (NAME "??tailwatchd - chkservd"?", UID 0) written by PID 16873 at 1521090336 at /usr/local/cpanel/Cpanel/SafeFile.pm line 868.
        Cpanel::SafeFile::_lock_wait("/var/run/chkservd.checking") called at /usr/local/cpanel/Cpanel/SafeFile.pm line 339
        Cpanel::SafeFile::_safelock("/var/run/chkservd.checking") called at /usr/local/cpanel/Cpanel/SafeFile.pm line 277
        Cpanel::SafeFile::safelock("/var/run/chkservd.checking") called at /usr/local/cpanel/Cpanel/TailWatch/ChkServd.pm line 252
        Cpanel::TailWatch::ChkServd::_run_checks(Cpanel::TailWatch::ChkServd=HASH(0x2940b58), Cpanel::TailWatch=HASH(0x1bf7ae0), 1521090786) called at /usr/local/cpanel/Cpanel/TailWatch/ChkServd.pm line 209
        Cpanel::TailWatch::ChkServd::run(Cpanel::TailWatch::ChkServd=HASH(0x2940b58), Cpanel::TailWatch=HASH(0x1bf7ae0), 1521090786) called at /usr/local/cpanel/Cpanel/TailWatch.pm line 739
        Cpanel::TailWatch::tail_logs(Cpanel::TailWatch=HASH(0x1bf7ae0)) called at /usr/local/cpanel/Cpanel/TailWatch.pm line 638
        eval {...} called at /usr/local/cpanel/Cpanel/TailWatch.pm line 606
        Cpanel::TailWatch::run(Cpanel::TailWatch=HASH(0x1bf7ae0)) called at /usr/local/cpanel/libexec/tailwatch/tailwatchd line 61
        main::run("--start") called at /usr/local/cpanel/libexec/tailwatch/tailwatchd line 38

Comments

5 comments

cPanelMichael

March 15, 2018 15:40
Hello, Can you let us know more information about the affected systems? EX: cat /etc/redhat-release cat /var/cpanel/envtype cat /usr/local/cpanel/version
Thank you.
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keat63

March 16, 2018 08:46
CentOs Release 6.9 (final) Standardroot@ 11.68.0.28 The error wasn't there this morning, but i'd still be interested to try and understand what it means.
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cPanelMichael

March 16, 2018 17:17
Hello, Could you open a support ticket using the link in my signature so we can take a closer look? Thank you.
0
keat63

March 19, 2018 08:26
Request ID is: 9368553
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keat63

March 20, 2018 15:10
Answer from Cpanel staff. The "UID 0 clobbering" warning means that when tailwatchd restarted a service, during the service restart it detected the service in question had lock files for a file or files the service or another process was writing to that referenced a non-existent process ID number. eg: [2018-02-12 09:53:35 +0000] warn [queueprocd] [2971] UID 0 clobbering stale lock file "??/etc/apache2/conf/httpd.conf.lock"?" (NAME "??/usr/local/cpanel/bin/safeapacherestart - safeaprestart - locking config"?", UID 0) written by PID 5833 at 1518428758 at /usr/local/cpanel/Cpanel/SafeFile.pm line 868. This would indicate the last time a change was made to the Apache configuration cPanel or another service placed a lock on that file to ensure nothing else would write to the file while the file was being changed. When the changes were complete the lock was never released for one reason or another but it's generally due to the process that created the lock ending prematurely. When the "safeaprestart" function was executed to restart Apache it detected the stale lock file on the httpd.conf file and logged a warning and then removed the lock file (clobbering) in order to allow Apache to start properly since it locks the file during service initialization to ensure no changes can be made to the config while it's loading: Basically, little to worry about
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