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Enabling GC logs in Apache Tomcat

There are so many way to analyze the performance of Application Server. 1 of those are called GC logs. GC logs is a log to monitor the movement of your application server’s memory usage. GC log is superb to analyze any kind of memory leaks or even analyze your optimization of your application. GC is actually stand for Garbage Collection, method in JVM to collecting all un-used or un-referenced object in memory to free up memory. So, lets get it on!

1. Enabling CATALINA_OPTS option and setting up the GC log enable parameter

You need to enable your CATALINA_OPTS parameter. CATALINA_OPTS is a parameter that allow you to specify a specific option during the startup of your tomcat server, such as the initial parameter for heap space, perm space, and so on. This can be done in 2 ways. In Windows Environment, you can create a new variable in your Environment Variable. Another simpler way, you can go to bin folder of your tomcat directory, find for startup.bat script. Open the script and you can set the CATALINA_OPTS variable. I prefer the second way to be explained since the first one only applicable for Windows user only.
So, open your startup.bat script, and add this code below :

set "CATALINA_OPTS=-Xloggc:log.gc"

at wherever you want (as long as it is put before :end and it is not in between if listing code 😀 ).
The -Xloggc is parameter for enabling GC logs. and log.gc is the name of file that will contain the log for memory. if you write like this, the GC will be created in bin folder right after server getting started up.

2. Start your apache tomcat

Next step, run your startup.bat. Right after the server getting started up, you will see in your bin folder, there will be a file called log.gc as per screen shot below :

If you can see this file, it means you have succesfully enabling your gc log for your performance monitor.

3. Analyze your GC logs

You might want to analyze your GC log since you have enable it and i’m pretty sure that you dont want to open the file using the editor since the content is such a horrible.
There are a lot of tools to analyze it, 1 sample that i take is HPjmeter, 1 of free application too analyze. You can google it to download 1 copy for you. Once you have installed it, you can drag your log.gc file into it, and you can see several options that you can use. Below is the sample screen shot from HPjmeter based on my log.gc :

GC Log Chart Example

GC Log Chart Example

GC Time Duration

Enjoy!!

 
4 Comments

Posted by on July 22, 2011 in English, Programming

 

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Tomcat 7.0 for Beginners

tomcat

tomcat


Tomcat, or officially named Apache Tomcat is a light-weight web container used for deploying and running web application based on Java. Just like apache for PHP as container, tomcat’s role is becoming a runtime for java web application. There are so many web container in the world but i choose tomcat as this tutorial since tomcat is quite easy to be understood and the server management is not that difficult. So for beginner, tomcat is a good kickstart to a real application server. For development, tomcat is a best friend since it has a very quick startup and it’s reliable for small number of applications.

INSTALLING TOMCAT 7.0

1. Download your Tomcat 7.0

Download the latest tomcat 7.0 in here.
Note : I prefer to use the distribution version one, so i recommend to choose any files except the installer version for windows since it is easy to be modified and to be moved to other computer.

2. Extract the downloaded file

Extract the file, then you will see a structure like this :

Folder Structure

After you finished this steps, you have succesfully installed your tomcat to your computer. Now let’s heading on the configuration.

CONFIGURING TOMCAT

1. Define administrator password

In tomcat, administrator term is defined as manager. In default, there will be no user in tomcat 7.0 as a manager. You have to add yours. To add new user, go to ${TOMCAT_INSTALLATION_DIR}/conf/ and open tomcat-users.xml.

At the first time you will see line 29 to 35 will be commented. Please uncomment these lines by removing tag. After that, add additional line for creating your user, and the code will be seen something like this :

<role rolename="tomcat"/>
<role rolename="role1"/>
<user username="tomcat" password="tomcat" roles="tomcat"/>
<user username="both" password="tomcat" roles="tomcat,role1"/>
<user username="role1" password="tomcat" roles="role1"/>
<user username="haka" password="haka" roles="manager-gui"/>

Note : Pay attention for the most bottom line. The username i set to “haka” and password set to “haka”. You can freely change these 2. But if you want the user to be manager, add manager-gui as the roles.

2. Configure local port

To configure any ports in Tomcat, go to ${TOMCAT_INSTALLATION_DIR}/conf/ and open file server.xml. After that, you can see whole configuration for server will be listed up there. For now, we will just customize port for host only. Go to line 67 in the file then you will see listing code like this :

You can change the port into any available port you like.
Note : If you have Oracle database installed, it might make a conflict since oracle listener use port 8080. So remember, if you have an oracle database installed, highly recommended that you change the port into other port, for example 8005, 8088, 8001, 8800,or whatever port you like ;). And also, you can change the connection timeout variable. This variable define how long will the system wait for starting the server. in this case, the value is 20000, means that the system will wait for 20 seconds IF the server is not tend to start.

I have oracle database installed in my current computer and i prefer port 8088, so that i change to port to 8088 :

<Connector port="8088" protocol="HTTP/1.1"
               connectionTimeout="20000" 
               redirectPort="8443" />

For a while, you have done with the minimum configuration for tomcat.

3. Starting the service

For starting the service, go to ${TOMCAT_INSTALLATION_DIR}/bin/ then execute file startup.bat. If everything is working fine, you will see a pop up uneditable command prompt windows like this :

Congratulations!! You have succesfully started your tomcat server 😀

4. Accessing root directory in server

Go to your browser and type this :

http://localhost:8088/

The 8088 port is really depend on what port you set in the server.xml. If you use 8080, then you have to type localhost:8080, and so on. If it’s successful, then you will see display like this :

5. Administering your server

You have set your username and password for the manager. If you want to administer your server, go to http://localhost:8088/manager/html. Then a pop dialog will be prompted, requesting user name and password.

Enter your username and password (for my case, user is haka and password is haka). If it’s succesfull, the screen will drive you to the manager screen :

Tomcat Administration

You can customize your server, customize the application deployed and you can even deploy your web application via this screen.

That’s tutorial for beginners of Tomcat. Next time i will prepare the tutorial of how deploying your first java web application. Stay tune ;). God bless!

 
14 Comments

Posted by on October 1, 2010 in English, Programming

 

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