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From André Warnier ...@ice-sa.com>
Subject Re: Tomcat Shutting Down by Itself?
Date Tue, 27 Jul 2010 13:46:38 GMT
Robinson, Eric wrote:
>> What kind of machine are you running these 163/164 
>> instances of Tomcat on, and when you are running them, 
>> what /does/ "free" say ?
> 
> I have two different servers with 164 instances of tomcat. Both servers
> have 2x quad-core 2.8Ghz Xeon processors with 32GB RAM. On the first
> server (app03), most instances of tomcat are configured with 64MB of
> Java heap. About 20% of them have 96-256MB. I almost never reboot this
> server (current uptime 61 days). Here's 'free' from app03.
> 
> 
> [root@app03 ~]# free
>              total       used       free     shared    buffers
> cached
> Mem:      33265832   30570260    2695572          0     296976
> 4562784
> -/+ buffers/cache:   25710500    7555332
> Swap:      2031608          0    2031608
> 
> 
> On the other server (app04), all instances of tomcat are configured with
> 512MB Java heap (-ms512M -mx512M). After 4 or 5 days of uptime, the
> server starts to swap a little. Then I reboot it and it is fine for
> several more days. As you can see from the following, it is about time
> for a reboot. If I do not reboot it tonight, by tomorrow or the next day
> it may be up to 1-2GB of swap. (It actually doesn't slow the server down
> much though. sar shows that it runs about 90% idle anyway, including
> iowait.
> 
> [root@app03 ~]# ssh app04 free
>              total       used       free     shared    buffers
> cached
> Mem:      33265832   32965812     300020          0     191248
> 3842092
> -/+ buffers/cache:   28932472    4333360
> Swap:      2031608       4288    2027320
> 
> 
That is very interesting information, thank you.
Intuitively, I would have never thought that it was /possible/ to run 160 or so instances

of Tomcat on anything but some type of very expensive hardware.
Granted, dual-Xeon CPU mainboards with 32 GB are not the low-end, but still.
One tends to forget how many megabytes fit in one gigabyte, and 160 X 64 MB is actually 
"only" 10 GB.

The data above, and your comments, seem to make unlikely the OOM hypothesis, unless you 
have one application suddenly acting up.
On which of those servers is the one Tomcat instance dying ? on both ?  Is that Tomcat 
instance running an application which the other ones don't ?
What kind of memory usage do the Tomcat instances have (in total, including the Heap) ? Do

you start them with any kind of other memory-related parameter for the JVM apart from -Xms

and -Xmx ?


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