Entirely removes the optipng, updates ghostscript fall back to also use WebP. Updates the conversion to use a multiprocessing pool

src/documents/parsers.py

@@ -150,11 +150,14 @@ def run_convert(
 
 
 def get_default_thumbnail() -> str:
+    """
+    Returns the path to a generic thumbnail
+    """
     return os.path.join(os.path.dirname(__file__), "resources", "document.png")
 
 
 def make_thumbnail_from_pdf_gs_fallback(in_path, temp_dir, logging_group=None) -> str:
-    out_path = os.path.join(temp_dir, "convert_gs.png")
+    out_path = os.path.join(temp_dir, "convert_gs.webp")
 
     # if convert fails, fall back to extracting
     # the first PDF page as a PNG using Ghostscript
@@ -319,29 +322,6 @@ class DocumentParser(LoggingMixin):
         """
         raise NotImplementedError()
 
-    def get_optimised_thumbnail(self, document_path, mime_type, file_name=None):
-        thumbnail = self.get_thumbnail(document_path, mime_type, file_name)
-        if settings.OPTIMIZE_THUMBNAILS and os.path.splitext(thumbnail)[1] == ".png":
-            out_path = os.path.join(self.tempdir, "thumb_optipng.png")
-
-            args = (
-                settings.OPTIPNG_BINARY,
-                "-silent",
-                "-o5",
-                thumbnail,
-                "-out",
-                out_path,
-            )
-
-            self.log("debug", f"Execute: {' '.join(args)}")
-
-            if not subprocess.Popen(args).wait() == 0:
-                raise ParseError(f"Optipng failed at {args}")
-
-            return out_path
-        else:
-            return thumbnail
-
     def get_text(self):
         return self.text