Limit number of completions in buffer to 10k by default.

src/prompt_toolkit/buffer.py

@@ -179,6 +179,9 @@ class Buffer:
         In case of a `PromptSession` for instance, we want to keep the text,
         because we will exit the application, and only reset it during the next
         run.
+    :param max_number_of_completions: Never display more than this number of
+        completions, even when the completer can produce more (limited by
+        default to 10k for performance).
 
     Events:
 
@@ -225,12 +228,13 @@ def __init__(
         accept_handler: BufferAcceptHandler | None = None,
         read_only: FilterOrBool = False,
         multiline: FilterOrBool = True,
+        max_number_of_completions: int = 10000,
         on_text_changed: BufferEventHandler | None = None,
         on_text_insert: BufferEventHandler | None = None,
         on_cursor_position_changed: BufferEventHandler | None = None,
         on_completions_changed: BufferEventHandler | None = None,
         on_suggestion_set: BufferEventHandler | None = None,
-    ):
+    ) -> None:
         # Accept both filters and booleans as input.
         enable_history_search = to_filter(enable_history_search)
         complete_while_typing = to_filter(complete_while_typing)
@@ -252,6 +256,7 @@ def __init__(
         self.enable_history_search = enable_history_search
         self.read_only = read_only
         self.multiline = multiline
+        self.max_number_of_completions = max_number_of_completions
 
         # Text width. (For wrapping, used by the Vi 'gq' operator.)
         self.text_width = 0
@@ -1739,6 +1744,13 @@ async def refresh_while_loading() -> None:
                         # If the input text changes, abort.
                         if not proceed():
                             break
+
+                        # Always stop at 10k completions.
+                        if (
+                            len(complete_state.completions)
+                            >= self.max_number_of_completions
+                        ):
+                            break
             finally:
                 refresh_task.cancel()