Analyzing Memory Usage: Java vs C++ Negligible?
- by Anthony
How does the memory usage of an integer object written in Java compare\contrast with the memory usage of a integer object written in C++? Is the difference negligible? No difference? A big difference? I'm guessing it's the same because an int is an int regardless of the language (?)
The reason why I asked this is because I was reading about the importance of knowing when a program's memory requirements will prevent the programmer from solving a given problem.
What fascinated me is the amount of memory required for creating a single Java object. Take for example, an integer object. Correct me if I'm wrong but a Java integer object requires 24 bytes of memory:
4 bytes for its int instance variable
16 bytes of overhead (reference to the object's class, garbage collection info & synchronization info)
4 bytes of padding
As another example, a Java array (which is implemented as an object) requires 48+bytes:
24 bytes of header info
16 bytes of object overhead
4 bytes for length
4 bytes for padding
plus the memory needed to store the values
How do these memory usages compare with the same code written in C++?
I used to be oblivious about the memory usage of the C++ and Java programs I wrote, but now that I'm beginning to learn about algorithms, I'm having a greater appreciation for the computer's resources.
