Showing posts with label java1.6.0_31. Show all posts
Showing posts with label java1.6.0_31. Show all posts

Saturday, April 25, 2015

My way of solving tomcat memory leaking issue

Recently, I did a mistake by accidentally commit a stupid static codes into a static method into production causing heap usage grow tremendously. Since the static method stay persisted with the object, tomcat has to restart often to free up the heap that get hold. So today, I will share my experience on how I solve it and I hope it will give you a way on how to solve this difficult problem.
First is the to end, I will summarize the sequence you need to investigate and find out the fix.

* learn on how to find the memory leak using google.
* one step at a time to trace until you successfully pin down the problem and fix it.

As you can read, only three general steps but for each step, I will talk more about it.

Always check your code by reading and tests! Best if you have someone experience and you can probably send your code for inspection. Remember, 4 eyes ball and 2 brains are better than 2 eyes ball and a brain. If you are using opensource project, most probably, the library are well tested and you should just spend time to investigate your codes. It's difficult especially for new programmer, but that should not stopped you to find out the problem. If you still cannot find out the problem, then you should start to search on search engine on how people solve it.
learn on how to find the memory leak using google.
Nobody is perfect and know everything, but if you are unsure, always google away. Google keyword such as java memory leak, tomcat memory leak or even best java coding practice. Pay attention on the first 10 links return by google and then read on blogging or even stackoverflow, it will give you knowledge that you never know of. Example of tools needed include jstat, jmap, jhat, and visualvm that can give you an idea what or even where might be the problem from. Remember, reading this material is a way of growing and it take times, so please be patience at this step and make sure u spend adequate amount of time and jot down important points mentioned and so you can use it on final step.

one step at a time to trace until you successfully pin down the problem and fix it.
Final step would probably repeating step 1 and step 2 slowly to determine the root cause. If you are using versoning system, you should really find out when was the last best working codes and start to check file by file where the problem was introduced. This is a TEDIOUS and DAUNTING process but this is effective to solving the root cause.
These steps were used by myself during determine the tomcat web application memory problem. Thank you and I hope you can benefit too.

Friday, December 20, 2013

A maven introduction.

So recently, I have been working on an opensource project and stumble upon maven. So I'm all ant guy (with ant background), and guess that to use maven should not be that difficult to start using it.

When you see a file in the java project, pom.xml, this should tell you that it is a maven configuration file. So for instance, in a as simple java project, it would look like
|project home |
| +-------+
+------+ src |
| +---+---+
| | +------+
| +-----+ main |
| | +--+---+
| | | +----------+
| | +----+ java |
| | | +----------+
| | | +----------+
| | +----+ resources|
| | +----------+
| | +------+
| +-----+ test |
| +--+---+
| | +----------+
| +----+ java |
| | +----------+
| | +----------+
| +----+ resources|
| +--------+ +----------+
+-----+ target |
| +--------+
| +--------+
+-----+ pom.xml|

The most basic command that you ever gonna use and use it very often would probably

mvn package

With above command, mvn will compile your class, run any tests and package the deliverable code and resources into target/my-app-1.0.jar . If mvn produced this jar, this should be enough and that the developer should be able to concentrate the java project.

But if you are adventurous and want to know more about maven, continue to read on. There are a few maven phases which you can issue the command. The following is the standard maven lifecycle with an ordered phases.

  • process-resources

  • compile

  • process-test-resources

  • test-compile

  • test

  • package

  • install

  • deploy

So in order to satisfy the library dependencies of your project, you should specify coordinate of the lib that it depends into pom.xml. You can use  this site to search for the libraries it depends.

I hope this answer a simple start up to use maven to assist in your java project. If you reach here and have further question, this link  and this link .