gh-109181: Speed up Traceback object creation by lazily compute the line number

[pablogsal]

• Issue: Exceptions slow in 3.11, depending on location #109181

[pablogsal]

From this test:

from time import perf_counter as time from timeit import repeat for e in range(2, 6): n = 10 ** e exec(f'''def f(): if 0 == 1:{'unreached;' * n} try: raise RuntimeError except RuntimeError: pass''') number = 10**6 // n t = min(repeat(f, number=number)) / number print(f'{n:6}{t * 1e6 :7.1f} μs') 

Before:

./python.exe bloch.py 100 1.4 μs 1000 10.5 μs 10000 102.4 μs 100000 1241.8 μs 

After:

./python.exe bloch.py 100 0.7 μs 1000 0.6 μs 10000 0.5 μs 100000 0.5 μs 

[miss-islington-app]

Thanks @pablogsal for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @pablogsal, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker abb15420c11d9dda9c89f74eac8417240b321109 3.12 

[miss-islington-app]

Sorry, @pablogsal, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker abb15420c11d9dda9c89f74eac8417240b321109 3.11 

[bedevere-app]

GH-111550 is a backport of this pull request to the 3.11 branch.

[bedevere-app]

GH-111551 is a backport of this pull request to the 3.12 branch.