Netty instrumentation causes memory leak and more

[raptium]

Describe the bug
io.netty.channel.ChannelFuture#addListener() is transformed to wrap the input listener with a helper class.
However the removeListener() removeListeners() counterparts are never transformed. Once a listener is added to the future, it can never be removed. This may cause memory leak and even logical incorrectness.

Steps to reproduce

import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.GenericFutureListener;

public class NettyChannelFutureDemo {
    public static void main(String[] args) {
        EmbeddedChannel channel = new EmbeddedChannel();
        for (int i = 0; i < 100; i++) {
            GenericFutureListener<Future<Object>> listener = future -> {
                System.out.println("channel closed");
            };
            channel.closeFuture().addListener(listener);
            channel.closeFuture().removeListener(listener); // not removed if netty instrumentation is on
        }
        try {
            channel.close().await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

What did you expect to see?
channel closed should never be printed since listeners are removed before the future completes.

What did you see instead?
channel closed is printed 100 times.

What version are you using?
v1.0.1

Environment
Compiler: AdoptOpenJDK 11.0.10
OS: Microsoft Windows 10

Additional context
N/A

[dkulig]

Hi, can I get some sort of an ETA when this will be released?

[iNikem]

We plan to release new version of the agent during the next several days.

[dkulig]

@iNikem thanks for the update. I can see that v1.2.0 has been released however this guy seems to not be included in the Bug fixes. Does that mean it will be included in the next release?

[mateuszrzeszutek]

Oh, the fix is there, but the note does not say anything about memleak explicitly:

• Netty 4.1 listeners could not be removed by application (Fix netty 4.1 instrumentation not removing future listeners #2851)

[dkulig]

thanks @mateuszrzeszutek