X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/71a9cb71e4cabe1444f68222c0bd7ad4324d6a5e..0d32948a1c78385f9305799c5cb47127492c4320:/sdk/python/arvados/events.py

diff --git a/sdk/python/arvados/events.py b/sdk/python/arvados/events.py
index 7e8cdc3282..94dd62b4ed 100644
--- a/sdk/python/arvados/events.py
+++ b/sdk/python/arvados/events.py
@@ -22,6 +22,11 @@ class EventClient(WebSocketClient):
             ssl_options['cert_reqs'] = ssl.CERT_NONE
         else:
             ssl_options['cert_reqs'] = ssl.CERT_REQUIRED
+
+        # Warning: If the host part of url resolves to both IPv6 and
+        # IPv4 addresses (common with "localhost"), only one of them
+        # will be attempted -- and it might not be the right one. See
+        # ws4py's WebSocketBaseClient.__init__.
         super(EventClient, self).__init__(url, ssl_options=ssl_options)
         self.filters = filters
         self.on_event = on_event
@@ -107,9 +112,9 @@ class PollClient(threading.Thread):
 
 def subscribe(api, filters, on_event, poll_fallback=15):
     '''
-    api: Must be a newly created from arvados.api(cache=False), not shared with the caller, as it may be used by a background thread.
+    api: a client object retrieved from arvados.api(). The caller should not use this client object for anything else after calling subscribe().
     filters: Initial subscription filters.
-    on_event: The callback when a message is received
+    on_event: The callback when a message is received.
     poll_fallback: If websockets are not available, fall back to polling every N seconds.  If poll_fallback=False, this will return None if websockets are not available.
     '''
     ws = None