Merge pull request #285 from alpacahq/verbose_stacktrace

Increase ws consume() exceptions verbosity

Author: Shlomi Kushchi

README.md

@@ -285,6 +285,20 @@ same `channel_pat` will overwrite the old handler.
 Deregisters the event handler function that was previously registered via `on` or
 `register` method.
 
+#### Debugging
+Websocket exceptions may occur during execution.
+It will usually happen during the `consume()` method, which basically is the 
+websocket steady-state.<br>
+exceptions during the consume method may occur due to:
+- server disconnections
+- error while handling the response data
+
+We handle the first issue by reconnecting the websocket every time there's a disconnection.
+The second issue, is usually a user's code issue. To help you find it, we added a flag to the 
+StreamConn object called `debug`. It is set to False by default, but you can turn it on to get a more
+verbose logs when this exception happens.
+Turn it on like so `StreamConn(debug=True)`  
+
 ## Logging
 You should define a logger in your app in order to make sure you get all the messages from the different components.<br>
 It will help you debug, and make sure you don't miss issues when they occur.<br>
@@ -293,7 +307,7 @@ The simplest way to define a logger, if you have no experience with the python l
 import logging
 logging.basicConfig(format='%(asctime)s %(message)s', level=logging.INFO)
 ```
----
+
 # Polygon API Service
 
 Alpaca's API key ID can be used to access Polygon API, the documentation for

alpaca_trade_api/stream2.py

@@ -2,6 +2,7 @@
 import json
 import os
 import re
+import traceback
 from asyncio import CancelledError
 
 import websockets
@@ -183,7 +184,9 @@ def __init__(
             secret_key: str = None,
             base_url: URL = None,
             data_url: URL = None,
-            data_stream: str = None):
+            data_stream: str = None,
+            debug: bool = False
+    ):
         self._key_id, self._secret_key, _ = get_credentials(key_id, secret_key)
         self._base_url = base_url or get_base_url()
         self._data_url = data_url or get_data_url()
@@ -196,6 +199,7 @@ def __init__(
         else:
             _data_stream = 'alpacadatav1'
         self._data_stream = _data_stream
+        self._debug = debug
 
         self.trading_ws = _StreamConn(self._key_id,
                                       self._secret_key,
@@ -293,6 +297,8 @@ def run(self, initial_channels: List[str] = []):
             except Exception as e:
                 m = 'consume cancelled' if isinstance(e, CancelledError) else e
                 logging.error(f"error while consuming ws messages: {m}")
+                if self._debug:
+                    traceback.print_exc()
                 loop.run_until_complete(self.close(should_renew))
                 if loop.is_running():
                     loop.close()