[Building Sakai] Sakai Instances 100% CPU Usage
Beth Kirschner
bkirschn at umich.edu
Tue Jul 3 08:36:47 PDT 2012
Relevant info from RHEL is at: https://access.redhat.com/knowledge/articles/15145 (other Linux distributions also have the problem though).
- Beth
On Jul 3, 2012, at 11:22 AM, Beth Kirschner wrote:
> There was a leap second this weekend (June 30, 8pm EDT) which we believe caused all our servers to hit 100% CPU usage simultaneously. Has anyone else in the Sakai community seen this? We're running:
> Linux 2.6.32-220.17.1.el6.x86_64
> java version "1.6.0_22"
>
> Thanks,
> - Beth
>
> Begin forwarded message:
>>
>>
>>
>> URL = http://wiki.os-ux.com/java-leap-second-bug-30-june-1-july-2012-fix/
>>
>>
>>
>> java leap second bug – 30 June / 1 July 2012 – fix
>> If your java applications suddenly started to use 100% CPU, you’ve hit java leap second bug (actually it’s a bug in Linux kernel, just java programs seem to be severely affected).
>>
>> First, you may check if you have the following in your dmesg:
>>
>>
>> [10703552.860274] Clock: inserting leap second 23:59:60 UTC
>>
>> Fortunately the fix is straightforward:
>>
>> /etc/init.d/ntpd stop
>> date -s "$(date)"
>>
>> /etc/init.d/ntpd start
>>
>> (the other suggested way around the web would be date `date +"%m%d%H%M%C%y.%S"`, having the same effect).
>>
>> You don’t have to restart your java applications (tomcat, solr, wowza, or whatever using java); it should be enough to run the above commands.
>>
>> You may want to enable ntp the next day (there were some reports that enabling it makes java misbehave on some installations).
>>
>> Apparently this issue has knocked down lots of Linux servers running Debian, Ubuntu, CentOS and the like around the globe!
>>
>> read more
>>
>> (via wpkg.org)
>>
>> Author: Vucomir Ianculov on July 3, 2012
>> Category: Linux / Unix
>> Tags: date, java, kernel, linux, ntpd, Zimbra
>>
>>
>
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