May 20, 2025
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
        ct = time.time_ns()
        self.name = name
        self.msg = msg
        self.message = None
        #
        # The following statement allows passing of a dictionary as a sole
        # argument, so that you can do something like
        Return the message for this LogRecord after merging any user-supplied
        arguments with the message.
        """
        msg = str(self.msg)
        if self.args:
            msg = msg % self.args
        return msg
        if self.message is None:
            msg = str(self.msg)
            if self.args:
                msg = msg % self.args
            self.message = msg

        return self.message

 #
 #   Determine which class to use when instantiating log records.
        called to format the event time. If there is exception information,
        it is formatted using formatException() and appended to the message.
        """
        # note: LogRecord.getMessage() will set record.message already but
        #       custom LogRecord objects may not so it's assigned here anyway
        record.message = record.getMessage()
        if self.usesTime():
            record.asctime = self.formatTime(record, self.datefmt)
diff --git a/Misc/NEWS.d/next/Library/2025-05-20-13-18-23.gh-issue-122089.SkjbnT.rst b/Misc/NEWS.d/next/Library/2025-05-20-13-18-23.gh-issue-122089.SkjbnT.rst
 Cache LogRecord.getMessage() the first time the message is formatted. Patch
 by Carey Metcalfe.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -303,6 +303,7 @@ def __init__(self, name, level, pathname, lineno,
		ct = time.time_ns()
		self.name = name
		self.msg = msg
		self.message = None
		#
		# The following statement allows passing of a dictionary as a sole
		# argument, so that you can do something like
Expand DownExpand Up		@@ -395,10 +396,13 @@ def getMessage(self):
		Return the message for this LogRecord after merging any user-supplied
		arguments with the message.
		"""
		msg = str(self.msg)
		if self.args:
		msg = msg % self.args
		return msg
		if self.message is None:
		msg = str(self.msg)
		if self.args:
		msg = msg % self.args
		self.message = msg

		return self.message

		#
		# Determine which class to use when instantiating log records.
Expand DownExpand Up		@@ -708,6 +712,8 @@ def format(self, record):
		called to format the event time. If there is exception information,
		it is formatted using formatException() and appended to the message.
		"""
		# note: LogRecord.getMessage() will set record.message already but
		# custom LogRecord objects may not so it's assigned here anyway
		record.message = record.getMessage()
		if self.usesTime():
		record.asctime = self.formatTime(record, self.datefmt)
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Cache LogRecord.getMessage() the first time the message is formatted. Patch
		by Carey Metcalfe.