FocusIt - Make IT happens

Java and other IT related posts

Free Books

Recently I realized that github has become for me something, where I can spend hours. It become something like facebook or twitter. So, I decided to share some intresting repos.

This is incredibly short post.

I’ll just provide you a repositry where you can borrow something new in computer science/IT/software development.

Just open link and you’ll see what value it has. I hope :)

Free programming books

This repository gives you a list of free books on programming in many languages. So, you are very welcome to read and push your skills high.


Sometime ago I’ve realized that JVM has two major things, that affects JVM performance the most. It is Jist-In-Time compilation and, of course, Garbage Collection. I believe that jstat is a great tool that show what’s JIT/GC doing right now, and some statistics about JIT/GC activity.


Sometimes, as you probably know, there could be a situation when you would want to send some commands to a running JVM instance to get an idea what’s heppening in the VM. For example you might want to send a command to make a heap dump, print class histogram or something else. This is the case for jcmd utility. It can send a lot of diagnostic commands to a JVM throught a special diagnostic channel. And the only condition for it to be possible is that JVM should be running normally, it must not be freezed. For example when JVM makes a heap dump it can’t accept any diagnostic commands.


This small tool can be useful when someone wants to view PIDs of running JVMs on the host.

List of JVM instances

Just type jps and you’ll see running JVMs instances.

$ jps
17910 Jps
17884 org.eclipse.equinox.launcher_1.3.100.v20150511-1540.jar

But jps can do more.

Java Power Tools

Hi there! In this short post serie I’m going to tell you a bit about some use cases of “invisible” tools that JDK comes with. I had wondered of fact that many developers don’t know anything about invisible power of these jdk tools. All of these tools aimed to help understanding what is going on in running jvm.

List of invisible tools:

  • jps
  • jcmd
  • jstat
  • jstack
  • jmap
  • jhat

I will write about one tool at a time.

Next post dedicated to jps.

Octopress Cheat Sheet

Octopress posting workflow:

  1. rake new_post["Post title"]. Note, if you are zsh user don’t forget to escape [ and ]
  2. rake generate
  3. git add .
  4. git commit -am 'Post title'
  5. git push origin source
  6. rake deploy

Nice to Meet You!

Hello, and Welcome. My name is Denis Kirpichenkov, and I’m a Java developer who likes DevOps too ;) In my first post will tell you how to get very powerful Content Management System, and how to get free hosting for it.

I tried many times to start blogging, but again and again I failed. The one of reasons was CMS. I could find content system to fit all of my needs. But now, I hope I found The One. I’m talking about Octopress. It is a powerful and simple Content Management System, which is for say is not a CMS at all. I’m will briefly describe its features in this post.

The next important step in blogging is a hosting. I tried Amazon’s EC2 tiny instance, Digital Ocean’s 5-dollars-per-month-vm. They didn’t fit my needs as well. I had to maintain them, and this process takes time. It is a big problem for me. I found the best hosting I’ve ever dreamt - GitHub. Below I will tell how to make GitHub to host your blog for FREE.