Message 256461 - Python tracker

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Author	bmwiedemann
Recipients	bmwiedemann, brett.cannon, ezio.melotti, mrabarnett, pitrou
Date	2015-12-15.15:54:56
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1450194897.19.0.781302598821.issue25870@psf.upfronthosting.co.za>
In-reply-to

Content
Many python scripts use textwrap to break base64-encoded strings from openssl into lines - e.g. https://bugs.launchpad.net/python-keystoneclient/+bug/1404402 and https://github.com/diafygi/acme-tiny/blob/master/acme_tiny.py#L166 Steps To Reproduce: time python -c "import textwrap; textwrap.wrap('x'9000, 64)" This has a complexity of O(n^2), meaning wrapping 18000 chars takes 4 times as long as 9000. one known workaround is to use textwrap.wrap('x'9000, 64, break_on_hyphens=False) this also has O(n^2) complexity, but is around 2000 times faster.

Many python scripts use textwrap to break base64-encoded strings from openssl into lines - e.g. https://bugs.launchpad.net/python-keystoneclient/+bug/1404402
and https://github.com/diafygi/acme-tiny/blob/master/acme_tiny.py#L166

Steps To Reproduce:
time python -c "import textwrap; textwrap.wrap('x'*9000, 64)"

This has a complexity of O(n^2), meaning wrapping 18000 chars takes 4 times as long as 9000.

one known workaround is to use
textwrap.wrap('x'*9000, 64, break_on_hyphens=False)

this also has O(n^2) complexity, but is around 2000 times faster.

History
Date	User	Action	Args
2015-12-15 15:54:57	bmwiedemann	set	recipients: + bmwiedemann, brett.cannon, pitrou, ezio.melotti, mrabarnett
2015-12-15 15:54:57	bmwiedemann	set	messageid: <1450194897.19.0.781302598821.issue25870@psf.upfronthosting.co.za>
2015-12-15 15:54:57	bmwiedemann	link	issue25870 messages
2015-12-15 15:54:56	bmwiedemann	create