Java 17: Memory Leak with ThreadPoolExecutor and Runnable Tasks in Spring Boot
I'm wondering if anyone has experience with I'm stuck on something that should probably be simple. This might be a silly question, but I'm experiencing a memory leak in my Spring Boot application using Java 17 when I utilize `ThreadPoolExecutor` to execute a number of `Runnable` tasks. After running the application for a few hours, the memory usage keeps increasing, and I suspect that the threads are not being released properly. Here's a simplified version of the code I am using: ```java import org.springframework.scheduling.annotation.Async; import org.springframework.stereotype.Service; import java.util.concurrent.Executors; import java.util.concurrent.ThreadPoolExecutor; @Service public class MyTaskService { private final ThreadPoolExecutor executor; public MyTaskService() { this.executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5); } @Async public void executeTask() { executor.submit(() -> { try { // Simulate some work Thread.sleep(1000); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } }); } } ``` I call `executeTask()` from a controller method, but after a while, the heap memory usage increases significantly. I have tried running a memory profiler (VisualVM) and noticed that the `Runnable` tasks are still in memory after completion, even though they don’t hold any strong references. I’ve also attempted to invoke `executor.shutdown()` in a `@PreDestroy` method of my service, but it seems like tasks are still retained in memory due to the internal workings of the executor. Additionally, I’ve verified that none of my tasks hold any unnecessary references to non-static variables or other objects. Is there a best practice I’m missing when using `ThreadPoolExecutor` with Spring Boot? What could be causing this memory leak, and how can I resolve it effectively? I'm working on a API that needs to handle this. Any ideas what could be causing this? What would be the recommended way to handle this?