Late 2008 I succeeded in persuading our database teacher to try out Glassfish for a new course on Web and Database programming for first year students. So before I knew it I was responsible for setting up a central Glassfish server for around 120 freshman programmers - UGH!
So how to best do this? This course has weekly lab-exercises and the teachers assistant need to grade them, so a distributed solution with a virtualbox image including netbeans and glassfish was not really the way forward - we needed a central server that the IT-dept. could maintain.
At DIKU we primarily use Gentoo Linux for our server park, so a standard HP DL360 G5 rack server was bought and a 64 bit version of Gentoo was installed from our customized Gentoo installation environment with Cfengine on top. Fortunately somebody had already made a Gentoo e-build package for Glassfish v2UR2, which easily could be updated. And within the hour I had a Glassfish server up and running - then the fun began - it needed configuration.
Our education environment is based on Sunray terminals, but uses Linux based application hosts. Our app-hosts had Eclipse installed, so at first I thought that Eclipse could be used to interact with the remote Glassfish-server, but NONONO! Our Eclipse was the basic Eclipse installation, which didn't support Java EE applications, so I tried installing the Eclipse Enterprise Edition which has a nice Glassfish plugin - but alas - this plugin only support a local installation of Glassfish and couldn't connect to a remote server, so I turned to Netbeans 6.5.
The full edition of Netbeans 6.5 did the trick, but STILL required a local installation of Glassfish for the plugin to connect to the remote host. OK - so far so good. Now the students should be able to connect to the server from within Netbeans and deploy their web-apps.
Then for the configuration of the server: 120 freshman programmers, which need to be able to run their web-apps without crashing the server or overwriting each others programs. I turned to the Sun Java System Application server 9.1 admin guide (which is Glassfish).
Glassfish has support for virtual hosts, so I was wondering whether just setting up 120 virtual hosts would do the trick. Unfortunately the Netbeans Glassfish plugin, does NOT (currently) support deployment to a specific virtual host, so each student had to be given his/her own Glassfish domain which include two dedicated ports - one for the admin interface and one to view the web-apps.
I ended up configuring each domain with the following setup:
I started /opt/glassfish/bin/asadmin in interactive mode and typed:
create-domain --user di080156 --adminport 11156 --instanceport 12156 di080156
Our student accounts are named di080XXX for the student year 2008/2009 where XXX is an increasing number. The UNIX UID for these accounts are always 11XXX where XXX is the same number as in the account name. So I chose that the adminport number should be the same as their UNIX UID, which can easily be looked up in the system by using the command
purps@ask ~/$ id di080156
uid=11156(di080156) gid=10000(del1user) groups=10000(del1user)
The instanceport number is the UNIX UID + 1000
The name of the domain is the same as the student account number, so when I do a 'list-domains' from asadmin, it will be clearly visible which domains might need to get started.
When creating a new domain an admin-user and an admin-password need to be set. The admin username will be the student account number, while the password will be db + the students birth date (DDMMYY) which I could easily pull from our central postgreSQL server.
Now it will be relatively easy for each student to remember the most important data (the servername, the admin-port, the username and the password) to connect to the Glassfish server through Netbeans:
Log on to DIKUs system from a sunray terminal
open a xterm with 'besthost bach'
open /opt/netbeans-6.5/bin/netbeans &
(wait while Netbeans starts)
Choose File | New Project...
Choose Java EE and the type of project
Choose a name and place for the project
Click on button Target Server - choose Add...
Server: Glassfish V2 - click Next
Platform Location: /opt/glassfish-v2ur2
Choose Register Remote Domain og choose Next
Host: glassfish.diku.dk
Port: enter your UNIX UID for your student account
Choose Next
Type Admin username: your di080xxx account name
Type Admin password: dbDDMMYY - where DDMMYY is your birthdate
Choose Finish
Tuning the Glassfish-server
Unfortunately starting 120 domains requires A HELL OF A LOT OF RAM. Each domain is by default started with 512 MB. Our server "only" had 20 GB RAM and 140 GB of swap, so I needed to decrease the RAM usage of each domains JVM. I found the document "Tuning your Glassfish - Performance Tips" presentation and went to /opt/glassfish/domains and for each domain I changed domain.xml from
<jvm-options>-Xmx512m</jvm-options>
to
<jvm-options>-Xms192m</jvm-options>
<jvm-options>-Xmx192m</jvm-options>
Afterwards each domain can be started with the command 'start-domain di080XXX' from asadmin, but after a while you don't want to start 120 domains manually, so a collegue of mine wrote a small script to start/stop all domains sequentially.
#!/bin/bash
ASADMIN=/opt/glassfish/bin/asadmin
DOMAINDIR=/opt/glassfish/domains
start_all(){
for DOMAIN in ${DOMAINDIR}/*; do
${ASADMIN} start-domain ${DOMAIN##*/}
done
}
stop_all(){
for DOMAIN in ${DOMAINDIR}/*; do
${ASADMIN} stop-domain ${DOMAIN##*/}
done
}
usage(){
cat <<-HERE
Usage: ${0} [command]
where command is one of
start start all domains
stop start all domains
restart first stop and then start all domains
HERE
}
case ${1} in
start)
start_all
;;
stop)
stop_all
;;
restart)
stop_all
start_all
;;
*)
usage
;;
esac
Now I am anxiously awaiting the students use of the server. The RAM usage is horrifying and it is swapping like crazy, and I am unsure if I should stuff even more physical RAM in the machine or try turning down the JVM RAM usage on each domain even more. Here is a snapshot of top:
top - 12:23:00 up 22:22, 2 users, load average: 1.55, 4.88, 4.06
Tasks: 212 total, 1 running, 211 sleeping, 0 stopped, 0 zombie
Cpu(s): 1.2%us, 0.3%sy, 0.0%ni, 79.3%id, 19.1%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 20600040k total, 20497768k used, 102272k free, 6736k buffers
Swap: 143338536k total, 18882040k used, 124456496k free, 18708k cached
Which user (blank for all):
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
23825 root 20 0 708m 166m 3820 S 1 0.8 1:49.27 java
7208 root 20 0 10560 1288 876 R 1 0.0 0:00.37 top
31804 root 20 0 784m 167m 3820 S 1 0.8 1:50.51 java
242 root 15 -5 0 0 0 D 0 0.0 4:08.55 kswapd0
394 root 20 0 706m 167m 3848 S 0 0.8 1:47.89 java
1537 root 20 0 787m 168m 3820 S 0 0.8 1:48.49 java
