[Building Sakai] An odd behavior when adding participants under a high load

[Shoji Kajita]

Hi David,

Ya, I'm also having doubt about some kernel caching issue like
KNL-972.

Our kernel is now rev 113905 with KNL-972.patch. The KNL-900 was fixed
by rev 113853 so that this odd behavior is still happening after the
fix.

Shoji

At Fri, 05 Oct 2012 15:42:18 +0200,
David Horwitz wrote:
> 
> Hi Shoji,
> 
> What version of the Kernel are you running? This sounds like a caching 
> issue - perhaps related to KNL-600. I know there has been some work on 
> fixes in this code recently ...
> 
> D
> On 10/05/2012 03:37 PM, Shoji Kajita wrote:
> > Hi Sakai Dev,
> >
> > We have started using our Sakai 2.9.x Pilot Server in real classes
> > since October 1st for 2012 second semester at Kyoto University, but we
> > have been struggling from an odd behavior.
> >
> > During a high load period (18:30-18:55 last evening as shown in the
> > jconsole summary screen shot http://db.tt/y8uNXzWM) produced by almost
> > 100 concurrent access from two physical class rooms, we saw the
> > following odd behavior when two instructors independently tried to add
> > students in their same course worksite:
> >
> >   1. the first instructor added about 50 students by using "Add
> >      Participants" of Site Info, but no students could not see the
> >      course worksite in their screen. Refreshing pages by Web browser
> >      or re-loging in did not help. After several minutes (maybe seven
> >      minutes or so), most of students could see the course worksite
> >      suddenly.
> >
> >      During the not-shown period, I (using admin account) sudo-ed a
> >      student who should have the right to access to the course
> >      worksite, and I could see the course worksite properly.
> >
> >   2. After 10 minutes, the second instructor did the almost same thing
> >      and no students could not see for five minutes or so.
> >
> > I have learned that the second instructor also had the same odd
> > behavior in his class during this evening class.
> >
> > I really appreciate if someone gives me any suggestions or pointers
> > for this odd behavior.
> >
> > Our Sakai 2.9.x Pilot Server is running under the following environment:
> >
> >    a. RedHat 6.2 on VMWare (16GB main memory, 2 CPUs)
> >
> >    b. Tomcat 7.0.29 with the following JAVA_OPTS:
> >
> >       #  12GB in total
> >       #    Eden size (3GB) = New size (4GB) - 2 x Survivor space size (512MB)
> >       #    Survivor space size (512MB) = New size (4GB) / survivor ratio (8)
> >
> >       export JAVA_OPTS='-server -Xms12288m -Xmx12288m -XX:PermSize=4096m -XX:MaxPermSize=4096m
> >       -XX:NewSize=4096m -XX:MaxNewSize=4096m -Djava.awt.headless=true -Dsun.lang.ClassLoader.allowArraySyntax=true
> >       -Dcom.sun.management.jmxremote -Dorg.apache.jasper.compiler.Parser.STRICT_WHITESPACE=false
> >       -Dorg.apache.jasper.compiler.Parser.STRICT_QUOTE_ESCAPING=false -Dhttp.agent=Sakai
> >       -Duser.language=ja -Duser.region=JP -Dfile.encoding=UTF-8 -XX:+DisableExplicitGC -XX:+PrintGCTimeStamps
> >       -XX:+PrintGCDetails -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:+CMSParallelRemarkEnabled
> >       -XX:+UseParNewGC -verbose:gc -XX:+PrintClassHistogram -XX:+HeapDumpOnOutOfMemoryError -XX:+PrintReferenceGC
> >       -Xloggc:$CH/logs/loggc.out'
> >
> >    c. Sakai 2.9.x (rev 113440) but kernel (rev 113905 with KNL-972.patch) and site-manage (rev 113912)
> >
> >    d. Oracle 11g R1 on RedHat 6.2/VMWare
> >
> > Best regards,
> > Shoji Kajita
> > ---
> > Shoji Kajita
> > IT Planning Office, IIMC, Kyoto University, Japan
> > http://about.me/shojikajita
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> 
> 
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