JRE 32bit vs 64bit

Question

I\'ve been using Java for a while now, and my typical ritual of setting up a new dev machine requires the norm of downloading and installing the latest JDK from Oracle\'s si

Answer 1

Do I need to understand the difference between 32-bit JVM and 64-bit JVM?

If you aren’t building a performance critical application, you don’t have to understand the difference. The subtle difference between 32-bit JVM and 64-bit JVM wouldn’t make much difference to your application. You can skip reading further

Does 64-bit JVM perform better than 32-bit JVM?

Most of us think 64-bit is bigger than 32-bit, thus 64-bit JVM performance will be better than 32-bit JVM performance. Unfortunately, it’s not the case. 64-bit JVM can have a small performance degradation than 32-bit JVM. Below is the excerpt from Oracle JDK documentation regarding 64-bit JVM performance:

“Generally, the benefits of being able to address larger amounts of memory come with a small performance loss in 64-bit VMs versus running the same application on a 32-bit VM.

The performance difference comparing an application running on a 64-bit platform versus a 32-bit platform on SPARC is on the order of 10-20% degradation when you move to a 64-bit VM. On AMD64 and EM64T platforms this difference ranges from 0-15% depending on the amount of pointer accessing your application performs.”

Does 32 bit JVM or 64 bit JVM matter anymore.

What are the things to consider when migrating from 32-bit JVM to 64-bit JVM? a. GC Pause times

The primary reason to migrate from 32-bit JVM to 64-bit JVM is to attain large heap size (i.e. -Xmx). When you increase heap size, automatically your GC pause times will start to go high, because now there is more garbage in the memory to clear up. You need to do proper GC tuning before doing the migration, otherwise your application can experience several seconds to few minutes pause time.

b. Native Library

If your application is using Java Native Interface (JNI) to access native libraries, then you need to upgrade the native libraries as well. Because 32-bit JVM can use only 32-bit native library. Similarly, 64-bit JVM can use only 64-bit native library.