Handling Concurrent Modifications of an Array in Java with Multiple Threads
I tried several approaches but none seem to work... I've spent hours debugging this and Can someone help me understand I've been banging my head against this for hours..... I'm relatively new to this, so bear with me. I'm currently working on a Java application (version 11) where I need to maintain a shared array across multiple threads. Each thread is expected to add elements to the array concurrently. However, I'm running into issues with `ArrayIndexOutOfBoundsException` and inconsistent data when multiple threads try to write to the same index at the same time. Here's a simplified version of what I've tried so far: ```java import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class ConcurrentArrayDemo { private static final int SIZE = 10; private static final int[] sharedArray = new int[SIZE]; public static void main(String[] args) { ExecutorService executor = Executors.newFixedThreadPool(5); for (int i = 0; i < 5; i++) { final int threadIndex = i; executor.submit(() -> { for (int j = 0; j < 5; j++) { try { sharedArray[threadIndex] = threadIndex * 10 + j; } catch (ArrayIndexOutOfBoundsException e) { System.out.println("Index out of bounds: " + threadIndex); } } }); } executor.shutdown(); } } ``` When I run this code, I sometimes see the `ArrayIndexOutOfBoundsException`, but more importantly, the contents of `sharedArray` are not what I expect after all threads complete execution. I suspect the issue has to do with concurrency and the lack of synchronization when multiple threads attempt to write to the same index. I've read about using `synchronized` blocks or `java.util.concurrent` collections, but I'm unsure how to implement this effectively without significantly degrading performance. How can I safely manage concurrent writes to this array while ensuring data integrity? Any best practices for multi-threaded access in this scenario would also be helpful. Any ideas what could be causing this? For reference, this is a production microservice. The stack includes Java and several other technologies. Has anyone else encountered this? This is happening in both development and production on Ubuntu 22.04. This is happening in both development and production on CentOS. Cheers for any assistance!