From e9b4ec614b66d11623b80471409c16a109f888d5 Mon Sep 17 00:00:00 2001
From: Craig Robson <craig@zhatt.com>
Date: Thu, 27 Jun 2024 09:44:40 -0700
Subject: [PATCH] gh-105623 Fix performance degradation in logging
 RotatingFileHandler (GH-105887)

The check for whether the log file is a real file is expensive on NFS
filesystems.  This commit reorders the rollover condition checking to
not do the file type check if the expected file size is less than the
rotation threshold.

Co-authored-by: Oleg Iarygin <oleg@arhadthedev.net>
---
 Lib/logging/handlers.py                                     | 6 +++---
 .../Library/2023-06-17-09-07-06.gh-issue-105623.5G06od.rst  | 2 ++
 2 files changed, 5 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2023-06-17-09-07-06.gh-issue-105623.5G06od.rst

diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index 410bd9851f3..0fa40f56e99 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -193,15 +193,15 @@ class RotatingFileHandler(BaseRotatingHandler):
         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
 
diff --git a/Misc/NEWS.d/next/Library/2023-06-17-09-07-06.gh-issue-105623.5G06od.rst b/Misc/NEWS.d/next/Library/2023-06-17-09-07-06.gh-issue-105623.5G06od.rst
new file mode 100644
index 00000000000..2890674aac4
--- /dev/null
+++ b/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.