How do you make your Java application memory efficient?
- by Boune
How do you optimize the heap size usage of an application that has a lot (millions) of long-lived objects? (big cache, loading lots of records from a db)
Use the right data type
Avoid java.lang.String to represent other data types
Avoid duplicated objects
Use enums if the values are known in advance
Use object pools
String.intern() (good idea?)
Load/keep only the objects you need
I am looking for general programming or Java specific answers. No funky compiler switch.
Edit:
Optimize the memory representation of a POJO that can appear millions of times in the heap.
Use cases
Load a huge csv file in memory (converted into POJOs)
Use hibernate to retrieve million of records from a database
Resume of answers:
Use flyweight pattern
Copy on write
Instead of loading 10M objects with 3 properties, is it more efficient to have 3 arrays (or other data structure) of size 10M? (Could be a pain to manipulate data but if you are really short on memory...)
