Formatting and improve comment

panimg/image_builders/tiff.py

@@ -2,12 +2,12 @@
 import re
 from collections import defaultdict
 from collections.abc import Callable, Iterator
+from concurrent.futures import ProcessPoolExecutor
 from dataclasses import dataclass, field
 from pathlib import Path
 from tempfile import TemporaryDirectory
 from typing import DefaultDict
 from uuid import UUID, uuid4
-from concurrent.futures import ProcessPoolExecutor
 
 import tifffile
 
@@ -337,9 +337,12 @@ def _convert(
 
             # If this is a globally importable value like "pyvips",
             # we ship it as string and look it up in _convert_to_tiff
-            # otherwise we pass the value directly
+            # otherwise we pass the value directly so that it can be
+            # used in the subprocess with proper resource isolation
             if converter in globals().values():
-                serialized_converter = [k for k, v in globals().items() if v == converter].pop()
+                serialized_converter = [
+                    k for k, v in globals().items() if v == converter
+                ].pop()
             else:
                 serialized_converter = converter
 

panimg/post_processors/tiff_to_dzi.py

@@ -1,10 +1,9 @@
 import logging
+from concurrent.futures import ProcessPoolExecutor
 
 from panimg.models import ImageType, PanImgFile, PostProcessorResult
 from panimg.settings import DZI_TILE_SIZE
 
-from concurrent.futures import ProcessPoolExecutor
-
 try:
     import pyvips
 except OSError:
@@ -28,7 +27,9 @@ def tiff_to_dzi(*, image_files: set[PanImgFile]) -> PostProcessorResult:
         if file.image_type == ImageType.TIFF:
             try:
                 with ProcessPoolExecutor(max_workers=1) as executor:
-                    result = executor.submit(_create_dzi_image, tiff_file=file).result()
+                    result = executor.submit(
+                        _create_dzi_image, tiff_file=file
+                    ).result()
             except Exception as e:
                 logger.warning(f"Could not create DZI for {file}: {e}")
                 continue