How can you optimize Java memory and performance?

Optimizing Java memory and performance is like making your computer run faster and smoother. First, clean up unused stuff (objects) to free up space. Imagine it's like tidying your room to make it less crowded. Next, use efficient code techniques, like shortcuts, to do tasks quicker. Think of it as finding a faster route to school. Also, reuse things instead of making new ones, just like reusing your water bottle instead of buying a new one each time. Finally, regularly check for problems (bugs) and fix them, similar to fixing a leaky faucet. By doing these, you'll help your Java programs run faster and use less memory, making them work better overall.

In my experience, customers often raise their maximum heap size as large as possible which results in wasted memory and long pauses as described in the article. A general helpful rule I've shared is to set the max memory to 125% the "average highest usage" of the trend - which usually results in better performance.

Try to choose a GC which removes garbage in parallel with program execution. There are many such GCs nowadays, the most prominent ones being G1 GC and Z GC. G1 tries to minimize count of pauses and improve throughput by dividing the heaps into multiple regions and collect smaller regions first. Z GC is designed to provide ultra-low pause times. There is an interesting one I came across recently, which is Azul G4 GC, which is designed for high performance and low latency requirements. It mainly uses concurrent, BUT pauseless collection techniques, unlike the others which have pause times, however small.

Avoid making unnecessary objects. These take up more CPU cycles when they need to be garbage collected. - Be alert towards making new objects whenever using autoboxing, String() constructor, and generally using constructors to create objects only to use their logic instead of data - Prefer primitives instead of boxed primitives, as primitives are much lighter. - When using objects for logic, prefer making them by factory methods, not by ctor, as ctor would create new object every time it runs, but factory method gives option to reuse existing objects, which can lead to fewer objects in existence - Pay special attention when objects are getting created unnecessarily INSIDE a loop. More the iterations, more such objects would be created

We could also - Use Try-With-Resources (AutoCloseable): When working with resources like files, sockets, or database connections, use try-with-resources (Java 7 and later) to automatically close them when you are done. - Avoid Circular References Be cautious with circular references between objects, as these can prevent the garbage collector from reclaiming memory. - Finalize Method (Deprecated) Avoid using the finalize method, as it can lead to resource leaks if not implemented correctly. - Check Thread Locals: Be careful when using ThreadLocal variables. Make sure to remove them when they are no longer needed to prevent thread-related memory leaks.

Efficient data structures can significantly impact both memory and speed performance in your software applications. 👉 Efficient data structures are designed to use memory more judiciously. For example, using an ArrayList instead of a LinkedList for storing a list of items can reduce memory overhead because it uses contiguous memory blocks, whereas a LinkedList requires additional memory for each node. 👉Also Efficient data structures often come with optimized algorithms for common operations. For instance, a balanced binary search tree ensures that lookups, insertions, and deletions remain efficient even as the data grows. Moreover it also depends on your requirements too as I mentioned earlier in example.

Be cautious about adding new threads to the application. Each thread has a stack associated with it. I see way too often requirements creep in which the solution... "spawn a thread to ...." and you end up with a program that has 200+ threads, most of them sleeping.

After delving into the article, I'm nudged to emphasize the oft-neglected human element: readability and maintainability. As we dive deep into optimization, it's tempting to write code that's efficient but cryptic. Remember, future developers (or even you) might revisit this code. Prioritize clean, self-commenting code. Documentation, although not directly related to performance, ensures the sustainability of optimizations. Furthermore, consider the broader ecosystem: how does your Java application interact with databases, third-party services, or APIs? Optimizing Java in isolation might miss potential bottlenecks elsewhere. Lastly, continuous integration tools can automate performance checks, fostering a culture of consistent optimization.

- Testing and Code Review: We ignore checking for or accounting for memory leaks while writing unit tests or while reviewing the code. Implement comprehensive unit tests and code reviews to catch potential memory leak issues during development. - Review Third-Party Libraries: Carefully review and update third-party libraries used in your application. Some libraries may have memory leak issues, and newer versions may contain fixes.