From 2a68ed986e9d19dff5d09713a5a225879acba3cb Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 28 Jun 2024 11:09:38 +0200
Subject: [PATCH] [3.12] gh-105623 Fix performance degradation in logging
 RotatingFileHandler (GH-105887) (GH-121116)

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.

(cherry picked from commit e9b4ec614b66d11623b80471409c16a109f888d5)

Co-authored-by: Craig Robson <craig@zhatt.com>
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 1ae6bb844349ae..715bce785c11f9 100644
--- a/Lib/logging/handlers.py
+++ b/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
 
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 00000000000000..2890674aac4bbc
--- /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.