output: #fixed code
                                  protected void processEvent(final SelectionKey key) {
          IOSessionImpl session = (IOSessionImpl) key.attachment();
          try {
              if (key.isAcceptable()) {
                  acceptable(key);
              }
              if (key.isConnectable()) {
                  connectable(key);
              }
              if (key.isReadable()) {
                  session.resetLastRead();
                  readable(key);
              }
              if (key.isWritable()) {
                  session.resetLastWrite();
                  writable(key);
              }
          } catch (CancelledKeyException ex) {
              queueClosedSession(session);
              key.attach(null);
          }
      }
input: #vulnerable code 
                                  protected void processEvent(final SelectionKey key) {
          SessionHandle handle = (SessionHandle) key.attachment();
          IOSession session = handle.getSession();
          try {
              if (key.isAcceptable()) {
                  acceptable(key);
              }
              if (key.isConnectable()) {
                  connectable(key);
              }
              if (key.isReadable()) {
                  handle.resetLastRead();
                  readable(key);
              }
              if (key.isWritable()) {
                  handle.resetLastWrite();
                  writable(key);
              }
          } catch (CancelledKeyException ex) {
              queueClosedSession(session);
              key.attach(null);
          }
      } 
                              #location 12 
                              #vulnerability type THREAD_SAFETY_VIOLATION