Revert "fix: register shutting down process pool for early execution"

This reverts commit 4c716e5.

Author: georgeh0

python/cocoindex/subprocess_exec.py

@@ -19,6 +19,7 @@
 import asyncio
 import os
 import time
+import atexit
 from .user_app_loader import load_user_app
 from .runtime import execution_context
 import logging
@@ -62,18 +63,10 @@ def _get_pool() -> ProcessPoolExecutor:
     with _pool_lock:
         if _pool is None:
             if not _pool_cleanup_registered:
-                # CRITICAL: register with threading's early-exit list
-                reg = getattr(threading, "_register_atexit", None)
-                if callable(reg):
-                    reg(_shutdown_pool_at_exit)  # goes ahead of normal atexit
-                    _pool_cleanup_registered = True
-                else:
-                    # Fallback for odd Pythons: normal atexit (will run later)
-                    import atexit
-
-                    if not _pool_cleanup_registered:
-                        atexit.register(_shutdown_pool_at_exit)
-                        _pool_cleanup_registered = True
+                # Register the shutdown at exit at creation time (rather than at import time)
+                # to make sure it's executed earlier in the shutdown sequence.
+                atexit.register(_shutdown_pool_at_exit)
+                _pool_cleanup_registered = True
 
             # Single worker process as requested
             _pool = ProcessPoolExecutor(