Java 17: implementing Caching Results of Heavy Computation Using ConcurrentHashMap
I need help solving I've looked through the documentation and I'm still confused about I'm trying to implement a caching mechanism for storing the results of a heavy computation in Java 17, utilizing `ConcurrentHashMap` for thread safety... However, I'm running into unexpected behavior where the cache doesn't seem to retain the computed values as expected. Here’s a simplified version of my code: ```java import java.util.concurrent.ConcurrentHashMap; import java.util.function.Function; public class CacheManager { private final ConcurrentHashMap<String, Integer> cache = new ConcurrentHashMap<>(); public Integer compute(String key, Function<String, Integer> heavyComputation) { return cache.computeIfAbsent(key, heavyComputation); } } ``` I'm using this `CacheManager` class to compute values based on a key. The `heavyComputation` function is a lambda that performs a CPU-intensive calculation, which I want to cache. Here's how I'm using it: ```java CacheManager cacheManager = new CacheManager(); int result1 = cacheManager.compute("key1", k -> { /* heavy computation here */ return 42; }); int result2 = cacheManager.compute("key1", k -> { /* heavy computation here */ return 42; }); ``` What’s puzzling is that upon calling `compute` with the same key multiple times, the heavy computation is executed again instead of retrieving the cached value. I've also verified that the computation completes successfully and returns the expected value, but the cache doesn’t seem to retain it. I've checked for multithreading issues, and it seems to be working in isolation, but when I run it in a concurrent environment, it falls apart. I've tried adding debug statements to log the calls and cache size, and it appears that the cache size increments with each call, indicating that new entries are being created. Additionally, I'm not seeing any exceptions or errors being thrown. Is there something I’m missing in my implementation or any specific considerations when using `ConcurrentHashMap` in this context? Any help would be appreciated! This is for a CLI tool running on Windows 11. This is part of a larger mobile app I'm building. What am I doing wrong?