#fixed code
                                public void start() throws IOException {
        if (selectorThreadFactory == null) {
            selectorThreadFactory = Executors.defaultThreadFactory();
        }
        if (executor == null) {
            executor = IoUtils.directExecutor();
        }
        for (int i = 0; i < readSelectorThreads; i ++) {
            readers.add(new NioSelectorRunnable());
        }
        for (int i = 0; i < writeSelectorThreads; i ++) {
            writers.add(new NioSelectorRunnable());
        }
        for (int i = 0; i < connectionSelectorThreads; i ++) {
            connectors.add(new NioSelectorRunnable());
        }
        for (NioSelectorRunnable runnable : readers) {
            selectorThreadFactory.newThread(runnable).start();
        }
        for (NioSelectorRunnable runnable : writers) {
            selectorThreadFactory.newThread(runnable).start();
        }
        for (NioSelectorRunnable runnable : connectors) {
            selectorThreadFactory.newThread(runnable).start();
        }
    }
#vulnerable code 
                                public void start() throws IOException {
        if (selectorThreadFactory == null) {
            selectorThreadFactory = Executors.defaultThreadFactory();
        }
        if (executor == null) {
            executor = executorService = Executors.newCachedThreadPool();
        }
        for (int i = 0; i < readSelectorThreads; i ++) {
            readers.add(new NioSelectorRunnable());
        }
        for (int i = 0; i < writeSelectorThreads; i ++) {
            writers.add(new NioSelectorRunnable());
        }
        for (int i = 0; i < connectionSelectorThreads; i ++) {
            connectors.add(new NioSelectorRunnable());
        }
        for (NioSelectorRunnable runnable : readers) {
            selectorThreadFactory.newThread(runnable).start();
        }
        for (NioSelectorRunnable runnable : writers) {
            selectorThreadFactory.newThread(runnable).start();
        }
        for (NioSelectorRunnable runnable : connectors) {
            selectorThreadFactory.newThread(runnable).start();
        }
    } 
                            #location 6 
                            #vulnerability type THREAD_SAFETY_VIOLATION