Java 17: Memory Leaks from Circular References in Spring Boot Application with Caching
This might be a silly question, but I've been banging my head against this for hours. I've been struggling with this for a few days now and could really use some help. I'm experiencing a memory leak in my Spring Boot application that uses Java 17 and Caffeine for caching. I've implemented a service that caches results from a database query, but after running the application for a few hours, the memory usage climbs considerably, eventually leading to an OutOfMemoryError. I suspect the issue arises from circular references in my cached objects. My cache stores instances of a `User` class that have a list of `Order` objects, and each `Order` object references back to the `User` object for some metadata. Here's a simplified version of the classes: ```java public class User { private String id; private String name; private List<Order> orders; // Constructors, getters, and setters } public class Order { private String orderId; private User user; // Constructors, getters, and setters } ``` When I cache the `User` objects using Caffeine like this: ```java Cache<String, User> userCache = Caffeine.newBuilder() .maximumSize(10_000) .expireAfterWrite(10, TimeUnit.MINUTES) .build(); User user = userRepository.findById(userId); userCache.put(user.getId(), user); ``` I’ve tried using `WeakReference` in my `Order` class to avoid strong references back to `User`, but that caused my cached `User` objects to be evicted prematurely, leading to cache misses. Additionally, I’m using Spring’s `@Cacheable` annotation without much luck: ```java @Cacheable(value = "users", key = "#userId") public User getUser(String userId) { return userRepository.findById(userId); } ``` This approach still keeps full references, which I believe is causing the memory leak. I’ve tried profiling the application using VisualVM and noticed that the cached `User` objects are not being garbage collected, as they are still strongly referenced by their `Order` objects. How can I effectively manage caching with circular references in Spring Boot to prevent memory leaks? Are there best practices or design patterns that I should consider for my use case? My development environment is Ubuntu. Thanks in advance! For context: I'm using Java on Ubuntu. Am I missing something obvious? Any help would be greatly appreciated!