Posts Tagged ‘tutorial’

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Flexible Java Profiling And Monitoring Using The Netbeans Profiler

Tuesday, October 20th, 2009

cpuProfile I have tested a lot of those open source profiler. My preference goes definitely to the integrated Netbeans profiler. It was simply the easiest and unified solution adapted to all the different settings I ever met, including profiling java applications that (i) were not developed under netbeans (ii) were only in the form of standalone jar (iii) were running on a remote Linux machine for which no X server were running (i.e. no UI), and other cases.

Here I describe how in 3 simple steps you can profile any java application using the wonderful Netbeans profiler.

Step 1: Download and install the latest Netbeans version on your machine(s)

On the netbeans download page choose the version adapted for your environment (Windows,Linux,Solaris,Mac…) and download/install it. All the bundles contain the profiler so I choose the lightest one: the JavaSE. If you want to profile a program running on a remote machine(s), you’ll have to download/install it on each machine.

Step 2: Modify the command line that runs the java application that you want to profile/monitor

You just have to add an argument to the Java VM.
On windows, the argument to add is of the form:

 -agentpath:"C:\Program Files\NetBeans 6.7.1\profiler3\lib\deployed\jdk16\windows\profilerinterface.dll"="C:\Program Files\NetBeans 6.7.1\profiler3\lib,5140"

Replace the portion “C:\Program Files\NetBeans 6.7.1\profiler3″ by the correct path (located where you installed Netbeans). Keep 5140, it is the port on which the application will listen for a remote profiler session (that you can also perform locally, as in this tutorial).
On Linux, it is exactly the same, just look for the right path containing the profiler3 folder.
So the java command line of the application to profile should look something like:

java -agentpath:"C:\Program Files\NetBeans 6.7.1\profiler3\lib\deployed\jdk16\windows\profilerinterface.dll"="C:\Program Files\NetBeans 6.7.1\profiler3\lib,5140" MyApp param1 param2

When launching this command, you should see on your console a message saying:
Profiler Agent: Waiting for connection on port 5140 (Protocol version: 9)
meaning that the application is listening and waiting for a profiler session on port 5140.

Note the flexibility behind this approach: it allows you to add this simple argument to the exsiting command of (i) any java applications running inside eclipse (in that case just open the “Run configuration” windows, in the “Arguments” tab just add the -agentpath option in the “VM arguments” section) or other IDE than Netbeans, (ii) any remote java applications (iii) any standalone jar file, or whatever existing java command that runs any kind of java application you can imagine…

Step 3: Run the Netbeans profiler GUI

Just open Netbeans, profile -> attach profiler. Choose which kind of profiling/monitoring you need, you can also configure it.

attachProfiler

Press Attach. Note that the first time you attach a profiler it may fail since you have to calibrate the profiler (in that case, a simple textbox will tell you how, it takes seconds).

That’s it!! You can now see in real time which part of your application is the heaviest, estimate what its memory footprint, analyze the threads and much more.

memory

If you want even more, note that it also exists specific profilers for collections (HashMap, HashSet, ArrayList, …) like collection spy (not free).

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BeanShell Tutorial: Quick Start On Invoking Your Own Or External Java Code From The Shell

Saturday, October 17th, 2009

bshsplash3BeanShell is a lightweight scripting language that’s compatible with the Java language.
It provides a dynamic environment for executing Java code in its standard syntax but also allow common scripting conveniences such as loose types, commands, and method closures like those in Perl and JavaScript. It is considered so useful that it should became part of the J2SE at some time in the future (the BeanShell Scripting Language JSR-274 , has passed the voting process with flying colors).

Here I simply describe how to call you own code or any external existing code directly from the bean shell. You first have to download the last bean shell jar release. Let’s suppose that you put it in the directory “C:\libs” along with the famous Apache commons lang library. So we suppose that “C:\libs” contains two jars called bsh-2.0b4.jar and commons-lang-2.4.jar.

Open a command prompt and type:

java -cp C:\libs\bsh-2.0b4.jar;C:\libs\commons-lang-2.3.jar bsh.Interpreter

You should see a prompt “bsh %” indicating that the bean shell session has started. So here an example of session using the method getLevenshteinDistance from the StringUtils utility class of the apache commons lang package:

bsh % import  org.apache.commons.lang.StringUtils;
bsh % d = StringUtils.getLevenshteinDistance("Louisville Slugger", "Lousiville Slugger");
bsh % print(d);
2

Note that instead of having to type the precise import, you can type instead:

bsh % import *;

This will trigger a set of “mappings” between the shell and the external jars that you specified in your classpath. By doing this, just remember that you are importing every possible class accessible from the classpath so it may force you to type the full path of classes in the case that two classes exists with the same name in different packages (it happens more often than one may think).

A good intermediary solution is to define a file called .bshrc and to put there all the specific imports that you are usually using. Then, while invoking the interpreter, just set the java system property user.home to the directory containing the .bshrc file. Let’s say for example that it is located in “C:\app\bshconfig”, you just have to type:

java -Duser.home=C:\app\bshconfig -cp C:\libs\bsh-2.0b4.jar;C:\libs\commons-lang-2.3.jar bsh.Interpreter

Note that you can add to the java command any options that you need (for instance you can use -Xmx if you need to).

For a complete doc of bean shell commands, consult the bean shell documentation page.

For an eclipse plugin allowing you to perform auto-complete from the bean shell and other nice features, take a look at EclipseShell (I didn’t tested it yet but the site contains nice screencasts and documentation).

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5 Video Tutorials Of Small To Killer Eclipse Shortcuts

Sunday, October 11th, 2009

eclipse I believe that when you spend a significant percentage of your time on a specific software, it is an obligation to become “mouse-less” using it. Few years ago when I started to use the powerful eclipse shortcuts, I observed that my productivity was dramatically improving. You’ll be able to find a lot of posts promoting some lists of “Top 10 eclipse shortcuts” (I like this one). I believe that small video tutorials can show more easily (rather than a bunch of screenshots) the power that some shortcuts can unleash.

So here 5 small video tutorials of shortcuts ranging from small ones to killer ones, all of them together making my day on eclipse much more easier and productive. The first two are small ones but still nice and useful. The remaining ones are more advanced and really have impact since you can potentially use them every couple of line of codes.

  1. Ctrl + Alt + Arrow (up or down): duplicating lines.

    2. Impact on productivity: low to medium

  2. Alt + Arrow (up or down): moving lines

    3. Impact on productivity: low to medium

  3. Ctrl +1: How To Directly or Indirectly Use The Power Of Quick Fixes.

    4. Impact on productivity: huge

  4. Alt + Shift + L: Extract Local Variables

    5. Impact on productivity: medium

  5. Ctrl + Space: Beyond Auto Completion, The Template Assistant (+ customization)

    6. Impact on productivity: high if heavily customized

    Except those, I highly recommend to heavily use those five ones (for which I think a video is less useful):

    • Ctrl + Shift + R (open resources)
    • Ctrl + O (quick outline). Pressing Ctrl + O again will show inherited members.
    • Ctrl + E (quick switch editor). Very handy to navigate between files.
    • Alt + Shift + R (rename variable). A very powerful one since it resolves all the possible dependencies on the renamed variable (works also on filenames).
    • Ctrl + T (quick type hierarchy).

    Become as much mouse-less as possible in Eclipse. Don’t try to start using them all in one day, try to integrate one per day, even week. You’ll end up much more productive anyway.

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