Clarify event thread handling in the README

README.md

@@ -21,6 +21,14 @@ player = mpv.MPV(ytdl=True)
 player.play('https://youtu.be/DOmdB7D-pUU')
 ```
 
+Threading
+---------
+The ```mpv``` module starts one thread for event handling, since MPV sends events that must be processed quickly. The event queue has a fixed maxmimum size and some operations can cause a large number of events to be sent.
+
+If you want to handle threading yourself, you can pass ```start_event_thread=False``` to the ```MPV``` constructor and manually call the ```MPV``` object's ```_loop``` function. There is also an out-of-date branch on the repo that you can cherry-pick that brings in asyncio.
+
+All API functions are thread-safe. If one is not, please file an issue on github.
+
 Advanced Usage
 ==============
 ```python

mpv-test.py

@@ -90,7 +90,7 @@ class TestProperties(unittest.TestCase):
                         setattr(self.m, name, 1)
                         setattr(self.m, name, 1.0)
                         setattr(self.m, name, -1.0)
-                        setattr(self.m, name, math.nan)
+                        setattr(self.m, name, float('nan'))
                     elif ptype == str:
                         setattr(self.m, name, 'foo')
                         setattr(self.m, name, '')

mpv.py

@@ -397,7 +397,7 @@ def _event_loop(event_handle, playback_cond, event_callbacks, message_handlers,
 
 class MPV(object):
     """ See man mpv(1) for the details of the implemented commands. """
-    def __init__(self, *extra_mpv_flags, log_handler=None, **extra_mpv_opts):
+    def __init__(self, *extra_mpv_flags, log_handler=None, start_event_thread=True, **extra_mpv_opts):
         """ Create an MPV instance.
 
         Extra arguments and extra keyword arguments will be passed to mpv as options. """
@@ -419,11 +419,14 @@ class MPV(object):
         self._key_binding_handlers = {}
         self._playback_cond = threading.Condition()
         self._event_handle = _mpv_create_client(self.handle, b'py_event_handler')
-        loop = partial(_event_loop, self._event_handle, self._playback_cond, self._event_callbacks,
+        self._loop = partial(_event_loop, self._event_handle, self._playback_cond, self._event_callbacks,
                 self._message_handlers, self._property_handlers, log_handler)
-        self._event_thread = threading.Thread(target=loop, name='MPVEventHandlerThread')
-        self._event_thread.setDaemon(True)
-        self._event_thread.start()
+        if start_event_thread:
+            self._event_thread = threading.Thread(target=self._loop, name='MPVEventHandlerThread')
+            self._event_thread.setDaemon(True)
+            self._event_thread.start()
+        else:
+            self._event_thread = None
 
         if log_handler is not None:
             self.set_loglevel('terminal-default')