Handling ConcurrentModificationException when using ConcurrentHashMap with lambda expressions in Java 17
I'm converting an old project and I'm following best practices but I'm running into a `ConcurrentModificationException` while trying to iterate through a `ConcurrentHashMap` in a multi-threaded environment using Java 17. I have a simple application where multiple threads are updating the map, and I’m trying to process the entries using a lambda expression. Here’s the relevant code snippet: ```java import java.util.concurrent.ConcurrentHashMap; public class Example { private ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>(); public void updateMap() { // Simulating multiple updates from different threads map.put("key1", 1); map.put("key2", 2); } public void processMap() { map.forEach((key, value) -> { System.out.println(key + " : " + value); // Some processing that might cause updates if (value < 2) { map.put(key + "_updated", value + 1); } }); } } ``` I've synchronized the `updateMap` method to prevent simultaneous writes, but I still encounter the exception when executing `processMap()`. I thought `ConcurrentHashMap` was designed to handle concurrent access gracefully. I've also tried using `entrySet().parallelStream()` for the processing, but that didn’t work either. The exception message I get is: ``` Exception in thread "Thread-0" java.util.ConcurrentModificationException ``` What’s the best way to retrieve and process entries in a `ConcurrentHashMap` while ensuring that updates do not lead to `ConcurrentModificationException`? Any insights on the proper patterns to follow would be greatly appreciated! This is for a microservice running on Windows 11. Has anyone else encountered this?