Configure VisualVM on Ubuntu 14.10

VisualVM is a kind of data gathering software for application which are running under the Java Virtual Machines (JVM). This retrieve information related to the Java application, like heap size, heap dumps, RAM utilisation, CPU utilisation, thread count and so on. There is an special interface that they use for getting information from application ends and gathered information is analysed and displayed on the VisualVM dashboard. Remote application also can be monitored via VisualVM. Specially user can get snapshot of heat dumps also.

Follow the steps to install VisualVM on Ubuntu server.

# sudo apt-get install visualvm

# which viaualvm

# java -version

You can check the java is up & running up using the commands given above. And for testing purpose, I’m here using a Java testing application in the same host. Let’s open the visualVM and configure it to get the information of running applications.

# visualvm

if you need any help related to visualVM you can us,

# visualvm - -help

After open the VisualVM, then you will see the terms and condition that should be accepted. Please accept it and go ahead.

After you agreed to the license agreement you will be displayed the VisualVM home page. In this home page you can see the options that you are having on VisualVm. In the Left side all the options are available. The image given below shows the sample home page of VisualVM.

To test an application, here I’m going to run a test application which contains a digital clock. 

https://www.evernote.com/shard/s565/sh/3ebfc539-ebda-47e8-a2fe-82dcdbaa16a8/996543f83e4a7c0e/res/3828d431-438b-4ee9-9571-e1574ec774ad/demo.zip

Download this file and extract, then run the testing java application on a terminal, then you will see the Digital clock on a particular application window.

# sudo unzip demo.zip

# cd src/

# javac DemoApp.java

# java DemoApp

After running the testing application, you will see the analytics of the application on the VisualVM dashboard. Locally running all the applications are added automatically to the VisualVM. Sample dashboard image is given below.

How to Add a Remote Host’s Application 

In order to create a connection with a remote Java Application, can be used JMX connection with the remote host. JMX is Java Management Framework, which is used to monitoring, or manage any java based application which running remotely or locally. So this is a best way to use to monitor remotely running Java Application.

In order to run a particular Java application using JMX you have to add several settings on commands.

1. com.sun.management.jmxremote.port :state which port is assigned to the Application.
2. com.sun.management.jmxremote.ssl : State the SSL certificate settings.
3. com.sun.management.jmxremote.authenticate : State the remote Authentication settings.

As an example, here the command that was used to open the DemoApp,

java -Dcom.sun.management.jmxremote.port=3333 -Dcom.sun.management.jmxremote.ssl=false -

Dcom.sun.management.jmxremote.authenticate=false DemoApp

Before adding the remote application for VisualVM, user needs to add the remote host to the VisualVM dashboard. Go to the “Application" on left side and right-click on the "Remote Host”, then click on "Add Remote Host”, then you will be displayed window to add the remote host.

After adding the remote host, you can add whatever the application which are running on added remote host. So right-click on the remote host name and select "Add JMX Connection”, then enter the remote host name and the port number which was assigned previously. After adding those things you can see the added application is displayed under the remote host (Image given below).

After you double-click on the Application, dashboard will be loaded and retrieve analytics and data according to the application weight. In following image you can see, both application are in same dashboard.

In Visual VM dashboard consist of the four tabs. The descriptions for each tabs are given below. 

• Overview : Contains PID, Host name, arguments, heap dumb, so on, this provides basic idea of the running application.
• Monitor : Processor consuming, memori consuming likewise utilisation detail.
• Threads : List of entire threads, state of threads, running time, and so on.
• Sampler : Sampling information, like CPU, memory.

Finally, I can state that VisualVM can be used to get analytics and mange Java based applications for maximum throughput. 

Thank You.

Rolling Updates & Releases

Rolling update in the sense, update the existing version of an Application, Operating system etc, without interrupting the running systems. 

Most of the LINUX distribution are consisted of the rolling updated and rolling releases, they would be able to attend the updating process while running. So the users and developers are served by best patches and updates for the existing systems.

This rolling updates used several methodologies for updates the systems. one is deliver frequent small updates and patches, as an example arch LINUX would be taken. Another one is replace the old image of the operating system with the new changes, the changes are added to the updating process. The Ubuntu cover versions is an example for this.

Benefits of using Rolling updates and releases.

1. Easy to maintain the  enterprise level servers and datacenter and clouds with the rolling releases and updates.
2. Automatically  software applications and servers are get updated without any interruption.
3. Does not take too long time to upgrade to major releases as the fixed releases. Because the system updates frequently.

And there also a major disadvantage of having rolling updates, because if there is a bug in a update or new release that would be directly affected to the entire system.

But according to the review and experience most of the IT industries uses the rolling update supported systems.