Java Heap vs Cache

Question

I have a question with respect to performance optimization.

Which is faster with respect to retrieving, from a Cache or from Java's heap?

According to the definition which I got :-

https://www.google.co.in/search?client=ubuntu&channel=fs&q=cache+vs+heap&ie=utf-8&oe=utf-8&gfe_rd=cr&ei=G7V1Ve-xDoeCoAP6goHACg#channel=fs&q=difference+between+cache+and+RAM

And if storing my data in cache via my java code is faster than storing it in java heap, then should we always store data in cache if required for faster access for complex computations and results.?

Kindly guide which one is faster and the use case scenarios as to when what to be used over the other..

Thanks

Answer 1

You mix up different concepts.

The quote is:

The difference between RAM and cache is its performance, cost, and proximity to the CPU. Cache is faster, more costly, and closest to the CPU. Due to the cost there is much less cache than RAM. The most basic computer is a CPU and storage for data.

This is about Computer architecture and applies for all computers, regardless what programming language you are using. There is no way to directly control what data is inside the cache. The CPU cache will hold data that is requested very often automatically. Programmers can improve their programs to make it more "friendly" to a particular hardware architecture. For example if the CPU has only a small cache, the code could be optimized to work on a smaller data set.

A Java Cache is something different. This is a library that caches Java objects, e.g. to save requests to an external service. A Java Cache, can store the object data in heap, outside the heap in separate memory or disk. Inside the heap has fastest access, since for any storage outside the heap the Objects need to be converted to byte streams (Called serialization or marshalling)