finally stress test

import javax.crypto.Cipher;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicLong;


class Scratch {

    static ThreadLocal<byte[]> tl = new ThreadLocal<>();
    static long last;
    static final Object lastLock = new Object();
    static long count;
    static AtomicLong cycles = new AtomicLong();

    public static void main(String[] args) {

        for (int i=0; i<50; i++) {
        spawn();
        }

        while (true) {
            try {
                Thread.sleep(10000);
            } catch (Exception ignored) {}
        }

    }

    private static void spawn() {
            new Thread(()->{
        cycles.getAndIncrement();
        int lim = ThreadLocalRandom.current().nextInt(10000) + 100;
                while (lim-- > 0) {
                    new Scratch().doIt();
                }
        spawn();
            }).start();
    }

    private void doIt() {

        byte [] stuff = new byte[1024];
        ThreadLocalRandom.current().nextBytes(stuff);

        tl.set(stuff);

        try {
            uselessWork();
        } catch (Exception e) {
            dumpException(e);
        } finally {
            tl.remove();
        }

        if (tl.get() != null) {
            System.out.println("Finally broke");
            System.exit(1);
        }

        long now = System.currentTimeMillis();
        synchronized (lastLock) {
            if (now - last > 10000) {
                last = now;
                System.out.println("I are OK "+(++count) + " " + cycles.get());
            }
        }

    }

    private void dumpException(Throwable e) {
        try {
            try (FileOutputStream fos = new FileOutputStream("/dev/null"); OutputStreamWriter w = new OutputStreamWriter(fos); PrintWriter pw = new PrintWriter(
                    w)) {
                e.printStackTrace(pw);
            }
        } catch (Exception e2) {
            e2.printStackTrace();
            System.exit(1);
        }
    }

    private void uselessWork() throws Exception {

        Cipher c = Cipher.getInstance("AES_192/CFB/NoPadding");
        byte [] data = c.update(tl.get());
        byte [] fin = c.doFinal();

        if (fin.length == 0) { fin = data; }

        if (ThreadLocalRandom.current().nextDouble() > 0.5) {
            throw new IllegalArgumentException(toStr(fin));
        }

    }

    static private String toStr(byte[] b) {
        StringBuilder sb = new StringBuilder();
        for (byte ib : b) {
            sb.append(ib);
        }
        return sb.toString();
    }

}