Fix cleanup of simple servers. (#1294)

* Fix clean up of simple servers.

* CHANGELOG

Author: danielballan

CHANGELOG.md

@@ -7,8 +7,10 @@ Write the date in place of the "Unreleased" in the case a new version is release
 
 ### Fixed
 
-- Explicitly specified `"Content-Type": "application/json"` in the request headers to
-  comply with stricter payload parsing in FastAPI >= 0.132.0.
+- Explicitly specified `"Content-Type": "application/json"` in the request
+  headers to comply with stricter payload parsing in FastAPI >= 0.132.0.
+- Servers started by the new function `tiled.client.simple` did not stop
+  cleanly at interpreter shutdown, causing a hangup.
 
 ## v0.2.5 (2026-02-20)
 

tiled/client/constructors.py

@@ -1,7 +1,7 @@
-import atexit
 import collections
 import collections.abc
 import pathlib
+import threading
 import warnings
 from typing import Optional, Union
 from urllib.parse import parse_qs, urlparse
@@ -316,4 +316,9 @@ def _cleanup_servers():
 
 
 SERVERS = []  # servers spawned using simple
-atexit.register(_cleanup_servers)
+# The threading module has its own (internal) atexit
+# mechanism that runs at thread shutdown, prior to the atexit
+# mechanism that runs at interpreter shutdown.
+# We need to intervene at that layer to close the portal, or else
+# we will wait forever for a thread run by the portal to join().
+threading._register_atexit(_cleanup_servers)