mina里的死锁检测

private void checkDeadLock() {
       // Only read / write / connect / write future can cause dead lock.
       if (!(this instanceof CloseFuture || this instanceof WriteFuture ||
             this instanceof ReadFuture || this instanceof ConnectFuture)) {
           return;
       }

       // Get the current thread stackTrace.
       // Using Thread.currentThread().getStackTrace() is the best solution,
       // even if slightly less efficient than doing a new Exception().getStackTrace(),
       // as internally, it does exactly the same thing. The advantage of using
       // this solution is that we may benefit some improvement with some
       // future versions of Java.
       StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();

       // Simple and quick check.
       for (StackTraceElement s: stackTrace) {
           if (AbstractPollingIoProcessor.class.getName().equals(s.getClassName())) {
               IllegalStateException e = new IllegalStateException( "t" );
               e.getStackTrace();
               throw new IllegalStateException(
                   "DEAD LOCK: " + IoFuture.class.getSimpleName() +
                   ".await() was invoked from an I/O processor thread.  " +
                   "Please use " + IoFutureListener.class.getSimpleName() +
                   " or configure a proper thread model alternatively.");
           }
       }

       // And then more precisely.
       for (StackTraceElement s: stackTrace) {
           try {
               Class<?> cls = DefaultIoFuture.class.getClassLoader().loadClass(s.getClassName());
               if (IoProcessor.class.isAssignableFrom(cls)) {
                   throw new IllegalStateException(
                       "DEAD LOCK: " + IoFuture.class.getSimpleName() +
                       ".await() was invoked from an I/O processor thread.  " +
                       "Please use " + IoFutureListener.class.getSimpleName() +
                       " or configure a proper thread model alternatively.");
               }
           } catch (Exception cnfe) {
               // Ignore
           }
       }
   }

  这个死锁检测算法位于DefaultIoFuture中，策略是分两步进行，首先是用一个简单而快速的方法检测，然后再用一个更精确地方法来检测。 第一个方法通过getStackTrace获得当前的线程的整个堆栈的元素数组，然后遍历这个数组，看是否有某一层的调用的class是AbstractPollingIoProcessor，如果有，就是存在循环调用，出现死锁。这是因为AbstractPollingIoProcessor是实现IoProcessor的抽象类，包含一个Executor，创建线程处理任务，