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From "Holly, Michael" <mho...@talisentech.com>
Subject RE: High load on CPU from upload attempts
Date Thu, 09 Sep 2004 15:43:58 GMT
Yoav

I think I am going to redirect my top output to a file (3 sec samples)
and then try to correlate the rise in CPU with the activity in my
logs...

What do you think?


Michael



-----Original Message-----
From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com] 
Sent: Thursday, September 09, 2004 10:18 AM
To: Tomcat Users List
Subject: RE: High load on CPU from upload attempts



Hi,
Can you reproduce the behavior on a test server?  If so, you can run
Tomcat with a Profiler on the test server and see exactly where CPU time
is spent.

Another thing you can do if you can reproduce the behavior is check out
the new J2SE 5.0 debugging tools.

If you can't reproduce the behavior, you're in a tougher spot obviously.
What are you using to handle the upload, commons-fileupload?

Yoav Shapira
Millennium Research Informatics


>-----Original Message-----
>From: Holly, Michael [mailto:mholly@talisentech.com]
>Sent: Thursday, September 09, 2004 11:07 AM
>To: tomcat-user@jakarta.apache.org
>Subject: High load on CPU from upload attempts
>
>I am having a problem with high CPU utilization by my Tomcat (java) 
>process.
>
>First some background
>
>Sun V880
>Solaris 9
>java.runtime.name = Java(TM) 2 Runtime Environment, Standard Edition 
>java.vm.version = 1.4.1_06-b01 Tomcat 4.1.27
>MySQL 3.23.53
>Homegrown object cache (eliminates trips to database)
>DBCP
>
>We are running the 64 bit extensions for java.
>
>Application is a viewer of reports and is used to upload new reports. 
>Report sizes are anywhere from 2k to 800 MB.  Users can only view at 
>most 1500 pages (~10MB) at any one time.
>
>400 total users.  50 fairly active users. maybe 4 concurrent tops
>
>Client in almost all cases is IE 6 using https over a VPN
>
>CPU utilization for java is usually < 2%
>
>Here is a top when java is out of control
>
>load averages:  2.42,  2.43,  2.39      hou-ftp
>09:45:50
>88 processes:  85 sleeping, 1 stopped, 2 on cpu
>CPU states: 51.9% idle, 31.8% user, 16.2% kernel,  0.0% iowait,  0.0% 
>swap
>Memory: 8.0G real, 5.8G free, 706M swap in use, 6.8G swap free
>
>   PID USERNAME THR PR NCE  SIZE   RES STATE   TIME FLTS    CPU COMMAND
> 29028 root      32  0   0  365M  325M cpu02  17.1H    1 26.27% java
> 15313 root       1 20   0 1872K 1416K sleep   9:47    0  2.98%
>resend.sh
> 24938 root       1 59   0 1912K 1456K sleep   9:50    0  0.05%
>nocmon.20040406
>  7123 mholly     1 29  10 2680K 1720K cpu06   1:09    0  0.04% top
>  5339 root       1 59   0 1904K 1432K sleep  19:02    0  0.02%
>get_pushes.sh
>     1 root       1 59   0 1304K  528K sleep  91:03    0  0.01% init
> 16772 root       1 59   0 1992K 1520K sleep  19:19    0  0.01%
>postmaster.sh
> 29503 root       1 59   0 4512K 2920K sleep   0:00    0  0.01% sshd
>   776 root       1 59   0  952K  720K sleep   0:00    0  0.01% sleep
>   702 root       1 59   0  952K  720K sleep   0:00    0  0.01% sleep
> 29429 root       1 59   0  952K  720K sleep   0:00    0  0.01% sleep
> 16785 root       1 59   0 1912K 1440K sleep  10:32    0  0.00%
>distribution.sh
> 11717 root       1 60   0 9488K 7848K sleep   0:23    0  0.00% arkvlib
>   229 root       1 59   0 1872K 1416K sleep   0:00    0  0.00% ksh
>  7753 root       1 59   0 4304K 3192K sleep  37.9H    0  0.00%
>burst_controlle
>
>My SA ran truss when the box was under distress, however, I do not 
>understand what I am looking at.  He says it is polling something.
>
>It appears this problem occurs after a user performs an upload to the 
>system. We have had problems with IE 6 and poor way it manages 
>authentication, however,
>we seem to have a work around for this.
>
>Not all users induce this load when they upload.  After the event in 
>question CPU bumps from < 2% to ~25% (1 CPU taken up) and stays there.

>If another event
>occurs then the CPU goes to ~50% (2 CPUs) etc.
>
>I think the event occurs when a user attempts and upload and it appears

>to be hung so they click the upload button again.  What
>
>What options do I have for instrumenting this and understanding what is

>going on? My SA wants to know if there are any switches we can apply to

>help us understand
>what is happening at a java level.
>
>Obviously, we are looking at upgrading the JVM.  Any other suggestions?
>
>Thanks
>
>Michael Holly
>Tailisen Technologies
>
>
>
>
>



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