PYTHON-4147 [v4.6]: Silence noisy thread.start() RuntimeError at shut…

…down (#1532)

Co-authored-by: Jib <jib.adegunloye@mongodb.com>

pymongo/periodic_executor.py

@@ -16,6 +16,7 @@
 
 from __future__ import annotations
 
+import sys
 import threading
 import time
 import weakref
@@ -92,7 +93,15 @@ def open(self) -> None:
  thread.daemon = True
  self._thread = weakref.proxy(thread)
  _register_executor(self)
- thread.start()
+ # Mitigation to RuntimeError firing when thread starts on shutdown
+ # https://github.com/python/cpython/issues/114570
+ try:
+ thread.start()
+ except RuntimeError as e:
+ if "interpreter shutdown" in str(e) or sys.is_finalizing():
+ self._thread = None
+ return
+ raise
 
  def close(self, dummy: Any = None) -> None:
  """Stop. To restart, call open().

test/test_monitor.py

@@ -16,6 +16,7 @@
 from __future__ import annotations
 
 import gc
+import subprocess
 import sys
 from functools import partial
 
@@ -79,6 +80,17 @@ def test_cleanup_executors_on_client_close(self):
  for executor in executors:
  wait_until(lambda: executor._stopped, f"closed executor: {executor._name}", timeout=5)
 
+ def test_no_thread_start_runtime_err_on_shutdown(self):
+ """Test we silence noisy runtime errors fired when the MongoClient spawns a new thread
+ on process shutdown."""
+ command = [sys.executable, "-c", "from pymongo import MongoClient; c = MongoClient()"]
+ completed_process: subprocess.CompletedProcess = subprocess.run(
+ command, capture_output=True
+ )
+
+ self.assertFalse(completed_process.stderr)
+ self.assertFalse(completed_process.stdout)
+
 
 if __name__ == "__main__":
  unittest.main()