python: Accept Optional[FrameType] in signal handlers.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

tools/test-queue-worker-reload

@@ -5,6 +5,7 @@ import subprocess
 import sys
 import time
 import types
+from typing import Optional
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
 
@@ -22,7 +23,7 @@ def check_worker_launch(run_dev: "subprocess.Popen[str]") -> bool:
     failed = False
     i = 0
 
-    def on_timer(signum: int, frame: types.FrameType) -> None:
+    def on_timer(signum: int, frame: Optional[types.FrameType]) -> None:
         nonlocal failed, i
         sys.stdout.write(".")
         sys.stdout.flush()

zerver/lib/debug.py

@@ -20,12 +20,13 @@ logger = logging.getLogger("zulip.debug")
 # (that link also points to code for an interactive remote debugger
 # setup, which we might want if we move Tornado to run in a daemon
 # rather than via screen).
-def interactive_debug(sig: int, frame: FrameType) -> None:
+def interactive_debug(sig: int, frame: Optional[FrameType]) -> None:
     """Interrupt running process, and provide a python prompt for
     interactive debugging."""
     d = {"_frame": frame}  # Allow access to frame object.
-    d.update(frame.f_globals)  # Unless shadowed by global
+    if frame is not None:
-    d.update(frame.f_locals)
+        d.update(frame.f_globals)  # Unless shadowed by global
+        d.update(frame.f_locals)
 
     message = "Signal received : entering python shell.\nTraceback:\n"
     message += "".join(traceback.format_stack(frame))

zerver/management/commands/process_queue.py

@@ -6,7 +6,7 @@ import threading
 from argparse import ArgumentParser
 from contextlib import contextmanager
 from types import FrameType
-from typing import Any, Iterator, List
+from typing import Any, Iterator, List, Optional
 
 from django.conf import settings
 from django.core.management.base import BaseCommand, CommandError
@@ -53,7 +53,7 @@ class Command(BaseCommand):
         logging.basicConfig()
         logger = logging.getLogger("process_queue")
 
-        def exit_with_three(signal: int, frame: FrameType) -> None:
+        def exit_with_three(signal: int, frame: Optional[FrameType]) -> None:
             """
             This process is watched by Django's autoreload, so exiting
             with status code 3 will cause this process to restart.
@@ -91,7 +91,7 @@ class Command(BaseCommand):
             queue_name = options["queue_name"]
             worker_num = options["worker_num"]
 
-            def signal_handler(signal: int, frame: FrameType) -> None:
+            def signal_handler(signal: int, frame: Optional[FrameType]) -> None:
                 logger.info("Worker %d disconnecting from queue %s", worker_num, queue_name)
                 worker.stop()
                 sys.exit(0)