recycler has problems recycling objects in a multi-threaded environment

[xiaoheng1]

Expected behavior

An object is collected in a multi-threaded environment and only exists in one queue.

Actual behavior

An object is collected in multiple queues in a multithreaded environment.

Steps to reproduce

public void testMultipleRecycleAtDifferentThread() throws InterruptedException {
        Recycler<HandledObject> recycler = newRecycler(1024);
        final HandledObject object = recycler.get();
        final AtomicReference<IllegalStateException> exceptionStore = new AtomicReference<IllegalStateException>();

        final CountDownLatch countDownLatch = new CountDownLatch(2);
        final Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                try{
                    object.recycle();
                }finally {
                    countDownLatch.countDown();
                }
                
            }
        });
        thread1.start();
        //thread1.join();

        final Thread thread2 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    object.recycle();
                } catch (IllegalStateException e) {
                    exceptionStore.set(e);
                } finally {
                    countDownLatch.countDown();
                }
            }
        });
        thread2.start();
        //thread2.join();
        
        countDownLatch.await();
        recycler.get();
        IllegalStateException exception = exceptionStore.get();
        if (exception != null) {
            throw exception;
        }
    }

Breakpoint debugging recycler.get() method, you will find that there are two queues in the stack, holding the same object.

Minimal yet complete reproducer code (or URL to code)

Netty version

4.1.59.Final-SNAPSHOT

JVM version (e.g. java -version)

1.8

OS version (e.g. uname -a)

masos

[normanmaurer]

Hmm... I can't see this. Can you make a screenshot ?

[xiaoheng1]

like this.

[normanmaurer]

@chrisvest can you have a look ?

[chrisvest]

@normanmaurer Yeah, I'll try to spend some time on this.