diffoscope/diff.py

@@ -539,6 +539,17 @@ class SideBySideDiff:
         Given two lists of lines, use python's difflib to make the diff a bit
         "smarter", as it better detects added lines (see !64)
         """
+
+        if len(l0) + len(l1) > 750:
+            # difflib.Differ.compare is at least O(n^2), so don't call it if
+            # our inputs are too large.
+            logger.debug(
+                "Not calling difflib.Differ.compare(x, y) with len(x) == %d and len(y) == %d",
+                len(l0),
+                len(l1),
+            )
+            return
+
         saved_line = None
         for line in self.differ.compare(l0, l1):
             # Skip lines with details as they don't matter to us

diffoscope/environ.py

@@ -30,7 +30,7 @@ def normalize_environment():
     """
 
     logger.debug(
-        "Normalising locale, timezone, etc. Inheriting PATH of %s",
+        "Normalising locale, timezone, etc. PATH is %s",
         os.environ.get("PATH", "(none)"),
     )
 

diffoscope/presenters/html/html.py

@@ -861,7 +861,7 @@ class HTMLPresenter(Presenter):
             if os.path.exists(path):
                 os.symlink(path, check_path)
                 logger.debug(
-                    "jquery found at %s and symlinked to %s", path, check_path
+                    "jQuery found at %s and symlinked to %s", path, check_path
                 )
                 return url.path