Skip to main content

MAX Memory For Your JVM

There is an interesting discussion going on the Java Posse Google Group on the maximum memory that can be allocated to a JVM.

Now if you are running a 32-bit system, then 4 GB is the maximum addressable memory. Of this, the OS (Windows)  takes about 2 GB (though it can be tweaked to take less according to a post on the Java forum), leaving 2 GB for your apps. You could theoretically assign this 2 GB to your JVM, but thread stacks are allocated memory outside of the JVM. So if your application uses a lot of threads, you will have to leave some space for the thread stacks.

Now if you use a 64-bit system, then you can allocate a LOT more memory to your JVM, but to do this your entire stack (CPU, OS, JVM, any other dependencies) needs to be 64-bit compliant. 

If you want an unlimited heap size for your JVM, you might want to check out Azul. John Reynolds wrote an interesting blog on scaling JVM's with Azul. 

By the way of you enjoy listening to podcasts and are into Java, then you absolutely must listen to the JavaPosse podcast. It is very informative and entertaining.



Notes: This text was originally posted on my earlier blog at http://www.adaptivelearningonline.net
Here are the comments from the original post

-----
COMMENT:
AUTHOR: Amish
EMAIL:
URL:
DATE: 01/17/2007 10:00:39 PM
hey.. sourceforge has serverfarm which they share with developers to work on it. You might be able to try various hardware available with them to check performance of systems and jvms...

COMMENT:
AUTHOR: Parag
DATE: 01/18/2007 05:30:14 PM
Hey Amish,
Good to hear from you. That is a good idea to check for peformance.

I will checkup with them for access, meanwhile, do you know if we need to apply or we can just create an account somewhere and start using their servers?

--
Parag

Comments

Popular posts from this blog

Commenting your code

Comments are an integral part of any program, even though they do not contribute to the logic. Appropriate comments add to the maintainability of a software. I have heard developers complain about not remembering the logic of some code they wrote a few months back. Can you imagine how difficult it can be to understand programs written by others, when we sometimes find it hard to understand our own code. It is a nightmare to maintain programs that are not appropriately commented. Java classes should contain comments at various levels. There are two types of comments; implementation comments and documentation comments. Implementation comments usually explain design desicisions, or a particularly intricate peice of code. If you find the need to make a lot of implementation comments, then it may signal overly complex code. Documentation comments usually describe the API of a program, they are meant for developers who are going to use your classes. All classes, methods and variables ...

Inheritance vs. composition depending on how much is same and how much differs

I am reading the excellent Django book right now. In the 4th chapter on Django templates , there is an example of includes and inheritance in Django templates. Without going into details about Django templates, the include is very similar to composition where we can include the text of another template for evaluation. Inheritance in Django templates works in a way similar to object inheritance. Django templates can specify certain blocks which can be redefined in subtemplates. The subtemplates use the rest of the parent template as is. Now we have all learned that inheritance is used when we have a is-a relationship between classes, and composition is used when we have a contains-a relationship. This is absolutely right, but while reading about Django templates, I just realized another pattern in these relationships. This is really simple and perhaps many of you may have already have had this insight... We use inheritance when we want to allow reuse of the bulk of one object in other ...

Planning a User Guide - Part 3/5 - Co-ordinate the Team

Photo by  Helloquence  on  Unsplash This is the third post in a series of five posts on how to plan a user guide. In the first post , I wrote about how to conduct an audience analysis and the second post discussed how to define the overall scope of the manual. Once the overall scope of the user guide is defined, the next step is to coordinate the team that will work on creating the manual. A typical team will consist of the following roles. Many of these roles will be fulfilled by freelancers since they are one-off or intermittent work engagements. At the end of the article, I have provided a list of websites where you can find good freelancers. Creative Artist You'll need to work with a creative artist to design the cover page and any other images for the user guide. Most small to mid-sized companies don't have a dedicated creative artist on their rolls. But that's not a problem. There are several freelancing websites where you can work with great creative ...