Micro-optimization

Start the background process immediately and use a zero timer only if
executing the process fails, thereby guaranteeing ordering without
imposing a delay on process start.

kitty/boss.py

@@ -2349,7 +2349,7 @@ def run_background_process(
         cwd_from: Optional[CwdRequest] = None,
         allow_remote_control: bool = False,
         remote_control_passwords: Optional[Dict[str, Sequence[str]]] = None,
-        notify_on_death: Optional[Callable[[int, Optional[Exception]], None]] = None,
+        notify_on_death: Optional[Callable[[int, Optional[Exception]], None]] = None,  # guaranteed to be called only after event loop tick
         stdout: Optional[int] = None, stderr: Optional[int] = None,
     ) -> None:
         import subprocess
@@ -2407,11 +2407,9 @@ def run(stdin: Optional[int], stdout: Optional[int], stderr: Optional[int]) -> N
                         with suppress(OSError):
                             os.close(fd)
                     if notify_on_death:
-                        try:
+                        def callback(err: Exception, timer_id: Optional[int]) -> None:
                             notify_on_death(-1, err)
-                        except Exception:
-                            import traceback
-                            traceback.print_exc()
+                        add_timer(partial(callback, err), 0, False)
                     else:
                         self.show_error(_('Failed to run background process'), _('Failed to run background process with error: {}').format(err))
 

kitty/rc/run.py

@@ -125,14 +125,10 @@ def on_death(exit_status: int, err: Optional[Exception]) -> None:
             for k, v in parse_env(x, env):
                 env[k] = v
 
-        def callback(timer_id: Optional[int]) -> None:
-            boss.run_background_process(
-                cmdline, env=env, stdin=stdin_data, stdout=stdout.fileno(), stderr=stderr.fileno(),
-                notify_on_death=on_death, remote_control_passwords=rcp, allow_remote_control=allow_remote_control
-            )
-        # Ensure that AsyncResponse is queued before the background process response
-        from kitty.fast_data_types import add_timer
-        add_timer(callback, 0, False)
+        boss.run_background_process(
+            cmdline, env=env, stdin=stdin_data, stdout=stdout.fileno(), stderr=stderr.fileno(),
+            notify_on_death=on_death, remote_control_passwords=rcp, allow_remote_control=allow_remote_control
+        )
         return AsyncResponse()
 
 

tools/cmd/at/socket_io.go

@@ -119,6 +119,7 @@ func run_stdin_echo_loop(conn *net.Conn, io_data *rc_io_data) (err error) {
 
 func simple_socket_io(conn *net.Conn, io_data *rc_io_data) (serialized_response []byte, err error) {
 	r := response_reader{}
+	r.pending_responses = make([][]byte, 0, 2)  // we read at most two responses
 	first_escape_code_sent := false
 	wants_streaming := io_data.rc.Stream
 	for {