I'm trying to create a float array that's nearly 3 billion elements long, but I'm running into issues because Java's array size parameter is an int, which means I can't exceed about 2.1 billion without hitting overflow and getting a negative size. I know I could use an ArrayList, but I'm looking for a more efficient solution. What are my options?
5 Answers
Using an ArrayList won't help much; it's also capped around 2.1 billion. If you want to stick with Java, consider using multiple arrays for workarounds. Alternatively, C, C++, or Rust can handle arrays of this size without problems. Python with numpy is also a strong option if you need to work with large datasets.
The 3 billion elements aren't that crazy. If each element is 4 or 8 bytes, you’re looking at 12 GB to 24 GB total. On a machine with 64 GB or more of RAM dedicated to the task, it's definitely doable. Have you explored custom collection libraries like Trove or fastutils? They offer optimized implementations for handling large datasets efficiently.
I'm really curious about your project. What exactly are you trying to achieve with these large arrays?
Honestly, you might not need to store billions of items in memory at once. There are usually better strategies out there for what you're trying to accomplish. Have you thought about redesigning your approach?
Many people in AI end up bumping into memory limits like this. Things have changed, and 4 GB isn't as impressive as it used to be. That's why languages like C have size_t to handle larger data.
It's a good idea to question why you need such a massive array. A common approach is to break your array down into several smaller arrays and treat them like a larger one when needed. It'll make handling the data a lot easier!
It sounds like your use case might not be the best fit for Java, and maybe a different language could suit your needs better.