From c72ff568c502a8e7feaca41f6426a853618d26d1 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 18 May 2024 08:34:01 +0530
Subject: [PATCH] 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             |  8 +++-----
 kitty/rc/run.py           | 12 ++++--------
 tools/cmd/at/socket_io.go |  1 +
 3 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/kitty/boss.py b/kitty/boss.py
index 414056559..37d2d6e88 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -2349,7 +2349,7 @@ class Boss:
         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 @@ class Boss:
                         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))
 
diff --git a/kitty/rc/run.py b/kitty/rc/run.py
index a5492a3c9..41eb26e00 100644
--- a/kitty/rc/run.py
+++ b/kitty/rc/run.py
@@ -125,14 +125,10 @@ The executed program will have privileges to run remote control commands in kitt
             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()
 
 
diff --git a/tools/cmd/at/socket_io.go b/tools/cmd/at/socket_io.go
index fcc86394b..fadfe50ec 100644
--- a/tools/cmd/at/socket_io.go
+++ b/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 {