https://mobile.twitter.com/SharplEr/status/1615372379831824384

ReaderThread.java

import java.io.Serializable;
import java.util.concurrent.atomic.LongAdder;

public class ReaderThread extends Thread {
    private static final LongAdder ops = new LongAdder();

    interface Reader extends Serializable {
        boolean advanceTo(int docId);
    }

    private final Reader reader;

    public ReaderThread(Reader reader) {
        this.reader = reader;
    }

    public final boolean advanceTo(int docId) {
        // Slow
        return ((Reader) (Object) reader).advanceTo(docId);

        // Fast
        // java.util.Objects.requireNonNull(reader);
        // return reader.advanceTo(docId);
    }

    public static void main(String[] args) throws Exception {
        new ReaderThread(docId -> (docId & 1) == 1).start();
        new ReaderThread(docId -> (docId & 1) != 0).start();

        while (true) {
            Thread.sleep(1000);
            System.out.println(ops.sumThenReset() + " ops/sec");
        }
    }

    @Override
    public void run() {
        while (benchmark()) {
            ops.increment();
        }
    }

    private boolean benchmark() {
        for (int i = 0; i < 1000000; i++) {
            if (advanceTo(i) && !(reader instanceof Serializable)) {
                return false;
            }
        }
        return true;
    }
}