Gerardo Corro wrote:
What would be the minimum memory needed by OS in order to have jvm/tomcat
running properly?
Our system will grow five times more and we were thinking to get a total of
20GB ram memory, we were planning to assign 18GB to jvm/tomcat and leave 2Gb to
the OS.
Is there a kind of rule for jvm-tomcat/os memory proportions needed?
There is no rule, but there was an earlier thread on this list with the message I quote
below, which provides an idea of how many distinct instances of Tomcat one /can/ run in
one machine with 32 GB of RAM. Divide by 164 to figure out how much memory one Tomcat
/might/ need. You may want to read the whole thread in the list archives there is
probably some information for you there.
Apart from that, I run a number of Linux servers with Tomcat (mostly 5.5 right now) and
the following "top" display if fairly typical.
top - 00:11:51 up 223 days, 13:58, 2 users, load average: 0.07, 0.02, 0.00
Tasks: 133 total, 1 running, 132 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2%us, 0.0%sy, 0.0%ni, 99.5%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 2054392k total, 1986820k used, 67572k free, 114660k buffers
Swap: 1951888k total, 58548k used, 1893340k free, 1027228k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3030 tomcat55 20 0 420m 162m 9168 S 0 8.1 73:22.22 java
The (32-bit) JVM of this particular Tomcat is configured with options "-Xms128M -Xmx128M"
in other words with a fixed size Heap of 128 MB. This is on a not-so-fast machine with 2
GB RAM in total, which runs plenty of other things.
I must say that your 3000 MB of Heap kind of makes my head spin. What kind of application
are you running that you would think you need as much ?
-------- Original Message --------
Subject: RE: Tomcat Shutting Down by Itself?
Date: Mon, 26 Jul 2010 21:35:03 -0700
From: Robinson, Eric <eric.robin...@psmnv.com>
Reply-To: Tomcat Users List <users@tomcat.apache.org>
To: Tomcat Users List <users@tomcat.apache.org>
> 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.
[r...@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.
[r...@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
--
Eric Robinson
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