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gh-109653: Improve import time of logging by lazy loading traceback #112995

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gh-109653: Improve import time of logging by lazy loading traceback #112995

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6c4e173
Speed up import time of logging module
danielhollas Dec 10, 2023
5ae66a2
Add NEWS entry
danielhollas Dec 12, 2023
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14 changes: 13 additions & 1 deletion Lib/logging/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,10 @@
To use, simply 'import logging' and log away!
"""

import sys, os, time, io, re, traceback, warnings, weakref, collections.abc
import sys, os, time, io, re, warnings, weakref, collections.abc

# Speed up import time by delaying traceback import until needed
traceback = None

from types import GenericAlias
from string import Template
Expand Down Expand Up @@ -653,6 +656,9 @@ def formatException(self, ei):
This default implementation just uses
traceback.print_exception()
"""
global traceback
if traceback is None:
import traceback
sio = io.StringIO()
tb = ei[2]
# See issues #9427, #1553375. Commented out for now.
Expand Down Expand Up @@ -1061,6 +1067,9 @@ def handleError(self, record):
The record which was being processed is passed in to this method.
"""
if raiseExceptions and sys.stderr: # see issue 13807
global traceback
if traceback is None:
import traceback
exc = sys.exception()
try:
sys.stderr.write('--- Logging error ---\n')
Expand Down Expand Up @@ -1601,6 +1610,9 @@ def findCaller(self, stack_info=False, stacklevel=1):
co = f.f_code
sinfo = None
if stack_info:
global traceback
if traceback is None:
import traceback
with io.StringIO() as sio:
sio.write("Stack (most recent call last):\n")
traceback.print_stack(f, file=sio)
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-12-12-08-44-30.gh-issue-109653.ZCUa8H.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Reduce the import time of :mod:`logging` module by ~15%. Patch by Daniel Hollas.