Graal concurrency test

GraalTest.java

package xyz.wagyourtail;

import org.graalvm.polyglot.Context;

import java.util.LinkedList;
import java.util.List;
import java.util.function.Function;

public class GraalTest {
    static List<Thread> threads = new LinkedList<>();
    static Context ctx = Context.newBuilder("js").allowAllAccess(true).build();
    
    public static void main(String[] args) {
        ctx.getBindings("js").putMember("test", new GraalTest());
        threads.add(Thread.currentThread());
        ctx.enter();
        ctx.eval("js", "console.log(test);" +
         "test.addThread(() => {while (1) {console.log('t1'); test.tick(); }});" +
         "test.addThread(() => {while (1) {console.log('t2'); test.tick(); }});");
         ctx.leave();
         runNextThreadOrTick();
         threads.remove(Thread.currentThread());
    }
    
    public void addThread(Function<Object[], Object> fx) throws InterruptedException {
        ctx.leave();
        Thread th;
        threads.add(th = new Thread(() -> {
            ctx.enter();
            fx.apply(new Object[0]);
            ctx.leave();
            runNextThreadOrTick();
            threads.remove(Thread.currentThread());
        }));
        synchronized (Thread.currentThread()) {
            th.start();
            Thread.currentThread().wait();
        }
        ctx.enter();
    }
    
    public static void runNextThreadOrTick() {
        int index = threads.indexOf(Thread.currentThread());
        if (index < threads.size() - 1) {
            Thread next = threads.get(index + 1);
            synchronized (next) {
                next.notify();
            }
        } else {
            runTick();
        }
    }
    
    public void tick() throws InterruptedException {
        ctx.leave();
        runNextThreadOrTick();
        synchronized (Thread.currentThread()) {
            Thread.currentThread().wait();
        }
        ctx.enter();
    }
    
    public static void runTick() {
        System.out.println("TICKED");
        
        if (threads.size() > 0) {
            synchronized (threads.get(0)) {
                threads.get(0).notify();
            }
        }
    }
}