develooper Front page | perl.perl5.porters | Postings from November 2016

Re: [perl #129802] COW performance problems with regexps

Thread Previous | Thread Next
Niko Tyni
November 4, 2016 10:20
Re: [perl #129802] COW performance problems with regexps
Message ID:
On Sun, Oct 30, 2016 at 11:29:10AM +0100, demerphq wrote:

> commit fe546b38f5a7481954f2f933acf85267578058b3
> Author: Yves Orton <>
> Date:   Sun Oct 30 11:02:57 2016 +0100
>     fix #129802: sv_grow: remove the overallocation for COW exemption
> for powers of 2

> commit 7fdc4f5848180e5ae502e30ea783733d0da04086
> Author: Yves Orton <>
> Date:   Sun Oct 30 10:56:36 2016 +0100
>     fix perl #129802 - overallocate in concat to ensure we can COW

> The first is potentially controversial. So it might get reverted. But
> I consider this ticket closed/fixed.

Many thanks for your work. Just in case you didn't notice, there was
earlier correspondence on this ticket including a comment from Dave with
pretty much the same conclusions.

As this seems to be a performance regression in 5.20 or so (and was
originally reported to Debian as one), is the fix something that could
be considered for the maint-* branches?
Niko Tyni

Thread Previous | Thread Next Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About