UN-2897 [FIX] Google Drive connector SIGSEGV crashes in Celery ForkPoolWorker processes (#1597)

UN-2897 [FIX] Google Drive connector SIGSEGV crashes in Celery ForkPoolWorker

Implements lazy initialization for Google Drive API client to prevent
segmentation faults when Celery forks worker processes.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

unstract/connectors/src/unstract/connectors/filesystems/google_drive/google_drive.py

@@ -1,6 +1,7 @@
 import json
 import logging
 import os
+import threading
 from datetime import datetime
 from pathlib import Path
 from typing import Any
@@ -48,14 +49,13 @@ class GoogleDriveFS(UnstractFileSystem):
             "refresh_token": settings["refresh_token"],
             GDriveConstants.TOKEN_EXPIRY: settings[GDriveConstants.TOKEN_EXPIRY],
         }
-        gauth = GoogleAuth(
-            settings_file=f"{os.path.dirname(__file__)}/static/settings.yaml",
-            settings={"client_config": self.client_secrets["web"]},
-        )
-        gauth.credentials = OAuth2Credentials.from_json(
-            json_data=json.dumps(self.oauth2_credentials)
-        )
-        self.drive = GDriveFileSystem(path="root", google_auth=gauth)
+        # Store settings file path for lazy initialization
+        self._settings_file = f"{os.path.dirname(__file__)}/static/settings.yaml"
+
+        # Lazy initialization - create client only when needed (after fork)
+        # This prevents SIGSEGV crashes in Celery ForkPoolWorker processes
+        self._drive = None
+        self._drive_lock = threading.Lock()
 
     @staticmethod
     def get_id() -> str:
@@ -97,7 +97,34 @@ class GoogleDriveFS(UnstractFileSystem):
         return True
 
     def get_fsspec_fs(self) -> GDriveFileSystem:
-        return self.drive
+        """Get GDrive filesystem with lazy initialization (fork-safe).
+
+        This method creates the Google Drive API client on first access,
+        ensuring it's created AFTER Celery fork to avoid SIGSEGV crashes.
+
+        The lazy initialization pattern ensures that gRPC-based Google API
+        clients are created in the child process after fork(), not in the
+        parent process before fork.
+
+        Returns:
+            GDriveFileSystem: The initialized Google Drive filesystem client
+        """
+        if self._drive is None:
+            with self._drive_lock:
+                # Double-check pattern for thread safety
+                if self._drive is None:
+                    logger.info("Initializing Google Drive client (lazy init after fork)")
+                    gauth = GoogleAuth(
+                        settings_file=self._settings_file,
+                        settings={"client_config": self.client_secrets["web"]},
+                    )
+                    gauth.credentials = OAuth2Credentials.from_json(
+                        json_data=json.dumps(self.oauth2_credentials)
+                    )
+                    self._drive = GDriveFileSystem(path="root", google_auth=gauth)
+                    logger.info("Google Drive client initialized successfully")
+
+        return self._drive
 
     def extract_metadata_file_hash(self, metadata: dict[str, Any]) -> str | None:
         """Extracts a unique file hash from metadata.