Fixed IOStream._handle_events (try/except block)

Fixed IOStream._handle_events (try/except block) to prevent
infinite loop when an unhandled exception occurs

tornado/iostream.py

@@ -189,6 +189,7 @@ class IOStream(object):
         if not self.socket:
             logging.warning("Got events for closed stream %d", fd)
             return
+        try:
             if events & self.io_loop.READ:
                 self._handle_read()
             if not self.socket:
@@ -210,6 +211,11 @@ class IOStream(object):
             if state != self._state:
                 self._state = state
                 self.io_loop.update_handler(self.socket.fileno(), self._state)
+        except:
+            logging.error("Uncaught exception, closing connection.",
+                          exc_info=True)
+            self.close()
+            raise
 
     def _run_callback(self, callback, *args, **kwargs):
         try: