SG-17861 Fixes an error that gets thrown when leaving a project on OSX.

python/tk_desktop/rpc.py

@@ -194,6 +194,13 @@ class RPCServerThread(threading.Thread):
     list/dictionary are treated as args/kwargs for the function call.
     """
 
+    # FIXME: Any errors raised here when closing won't actually be caught by
+    #  our tests, because the error happens in a separate thread. This can be solved
+    #  by catching and storing the exception and then raising it in the join method
+    #  as suggested here: https://stackoverflow.com/a/31614591/4223964
+    #  This is currently not implemented because it raises errors in our tests
+    #  that we at the time of writing don't have time to fix, but have no impact on user experience.
+
     # timeout in seconds to wait for a request
     LISTEN_TIMEOUT = 2
 
@@ -256,7 +263,7 @@ def wrapper(*args, **kwargs):
     def run(self):
         """
         Run the thread, accepting connections and then listening on them until
-        they are closed.  Each message is a call into the function table.
+        they are closed. Each message is a call into the function table.
         """
         logger.debug("server listening on '%s'", self.pipe)
         while self._is_closed is False:
@@ -278,10 +285,17 @@ def run(self):
                         raise
                     ready = False
             else:
-                # can use select on osx and linux
-                (rd, _, _) = select.select(
-                    [self.server._listener._socket], [], [], self.LISTEN_TIMEOUT
-                )
+                # Can use select on OSX and Linux.
+                try:
+                    (rd, _, _) = select.select(
+                        [self.server._listener._socket], [], [], self.LISTEN_TIMEOUT
+                    )
+                except select.error as e:
+                    if "Bad file descriptor" in e.args:
+                        # The socket was likely closed during this iteration of the loop
+                        # so we should break out of the loop.
+                        break
+                    raise
                 ready = len(rd) > 0
 
             if not ready:

tests/test_rpc.py

@@ -128,6 +128,11 @@ def server(fake_engine, request):
 
     :returns: A RPCServerThread instance.
     """
+
+    # FIXME: Any errors raised here when closing won't actually be caught by
+    #  our tests, because the error happens in a separate thread.
+    #  See the FIX ME in the RPCServerThread class for further details.
+
     server = RPCServerThread(fake_engine)
     server.register_function(fake_engine.pass_arg)
     server.register_function(fake_engine.pass_named_arg)