[3.12] gh-105623 Fix performance degradation in logging RotatingFileHandler (GH-105887)

Lib/logging/handlers.py

@@ -187,15 +187,15 @@ def shouldRollover(self, record):
         Basically, see if the supplied record would cause the file to exceed
         the size limit we have.
         """
-        # See bpo-45401: Never rollover anything other than regular files
-        if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
-            return False
         if self.stream is None:                 # delay was set...
             self.stream = self._open()
         if self.maxBytes > 0:                   # are we rolling over?
             msg = "%s\n" % self.format(record)
             self.stream.seek(0, 2)  #due to non-posix-compliant Windows feature
             if self.stream.tell() + len(msg) >= self.maxBytes:
+                # See bpo-45401: Never rollover anything other than regular files
+                if os.path.exists(self.baseFilename) and not os.path.isfile(self.baseFilename):
+                    return False
                 return True
         return False
 

Misc/NEWS.d/next/Library/2023-06-17-09-07-06.gh-issue-105623.5G06od.rst

@@ -0,0 +1,2 @@
+Fix performance degradation in
+:class:`logging.handlers.RotatingFileHandler`. Patch by Craig Robson.