Python Client: avoid thread self-join on stop()

py/client-ticking/src/pydeephaven_ticking/table_listener.py

@@ -211,24 +211,29 @@ def start(self) -> None:
 
     def stop(self) -> None:
         """Cancels the subscription to the table and stops the service thread. By the time this method returns, the
-        thread servicing the subscription will be destroyed, and the callback will no longer be invoked."""
+        thread servicing the subscription will be destroyed, and the callback will no longer be invoked.
+        This method joins the subscription servicing thread, unless stop() was called from that very thread.
+        This can happen if the user's callback calls stop()."""
 
         self._cancelled = True
         self._reader.cancel()
-        self._thread.join()
+        if threading.get_ident() != self._thread.ident:
+            self._thread.join()
 
     def _process_data(self):
         """This method continuously runs on a separate thread. It processes incoming Barrage messages, feeds them to
         the BarrageProcessor library, and, when the BarrageProcessor library produces a TableUpdate, calls the
         user-supplied callback with that TableUpdate."""
 
         try:
-            while True:
+            while not self._cancelled:
                 data, metadata = self._reader.read_chunk()
                 ticking_update = self._bp.process_next_chunk(data.columns, metadata)
                 if ticking_update is not None:
                     table_update = TableUpdate(ticking_update)
                     self._listener.on_update(table_update)
+        except StopIteration:
+            pass
         except Exception as e:
             if not self._cancelled:
                 self._listener.on_error(e)