fix: DaemonThreadPoolExecutor compat with Python 3.14

tools/daemon_pool.py

@@ -26,19 +26,39 @@
 
 from __future__ import annotations
 
+import sys
 import threading
 import weakref
 from concurrent.futures import ThreadPoolExecutor
 from concurrent.futures.thread import _worker
 
 __all__ = ["DaemonThreadPoolExecutor"]
 
+# Python 3.14 replaced ThreadPoolExecutor._initializer/_initargs with a
+# prepare_context() → (_create_worker_context, _resolve_work_item_task)
+# pattern, and changed _worker's signature from
+#   _worker(executor_ref, work_queue, initializer, initargs)   # 3.8–3.13
+# to
+#   _worker(executor_ref, ctx, work_queue)                     # 3.14+
+# The override below must branch on the running interpreter version.
+_PY314 = sys.version_info >= (3, 14)
+
 
 class DaemonThreadPoolExecutor(ThreadPoolExecutor):
     """ThreadPoolExecutor variant whose workers do not block process exit."""
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Belt-and-suspenders: on 3.14+ the stdlib __init__ no longer sets
+        # _initializer/_initargs.  Ensure they exist so any external code
+        # that reads them (or an older code path) doesn't AttributeError.
+        if not hasattr(self, "_initializer"):
+            self._initializer = None
+        if not hasattr(self, "_initargs"):
+            self._initargs = ()
+
     def _adjust_thread_count(self) -> None:
-        # Mirrors CPython's implementation (3.8–3.13) with two changes:
+        # Mirrors CPython's implementation with two changes:
         # daemon=True and no _threads_queues registration.
         if self._idle_semaphore.acquire(timeout=0):
             return
@@ -49,16 +69,30 @@ def weakref_cb(_, q=self._work_queue):
         num_threads = len(self._threads)
         if num_threads < self._max_workers:
             thread_name = "%s_%d" % (self._thread_name_prefix or self, num_threads)
-            t = threading.Thread(
-                name=thread_name,
-                target=_worker,
-                args=(
-                    weakref.ref(self, weakref_cb),
-                    self._work_queue,
-                    self._initializer,
-                    self._initargs,
-                ),
-                daemon=True,
-            )
+            if _PY314:
+                # Python 3.14+: _worker(executor_ref, ctx, work_queue)
+                t = threading.Thread(
+                    name=thread_name,
+                    target=_worker,
+                    args=(
+                        weakref.ref(self, weakref_cb),
+                        self._create_worker_context(),
+                        self._work_queue,
+                    ),
+                    daemon=True,
+                )
+            else:
+                # Python 3.8–3.13: _worker(executor_ref, work_queue, initializer, initargs)
+                t = threading.Thread(
+                    name=thread_name,
+                    target=_worker,
+                    args=(
+                        weakref.ref(self, weakref_cb),
+                        self._work_queue,
+                        self._initializer,
+                        self._initargs,
+                    ),
+                    daemon=True,
+                )
             t.start()
             self._threads.add(t)