Re: Performance Regression between sed 4.4 and sed 4.5+

[Jakub Martisko]

Sending some statistics, I've tried to use LANG=C which helped a bit,
but the performance is still worse than when using sed 4.4

These are with LANG=C.UTF-8
time ~/repos/Fedora/sed/sed-4.4/sed/sed -nf program.sed input > output_4.4

real    0m21.214s
user    0m20.641s
sys    0m0.510s


time ~/repos/Fedora/sed/sed-4.5/sed/sed -nf program.sed input > output_4.4

real    183m34.784s
user    179m23.097s
sys    3m51.128s

These with LANG=C
time LANG=C ~/repos/Fedora/sed/sed-4.4/sed/sed -nf program.sed input >
output_4.4

real    11m16.226s
user    8m39.261s
sys    2m34.840s


time LANG=C ~/repos/Fedora/sed/sed-4.5/sed/sed -nf program.sed input >
output_4.4

real    9m17.259s
user    7m11.610s
sys    2m3.557s

On Wed, Nov 22, 2023 at 11:28 AM Jakub Martisko <jamartis@redhat.com> wrote:
>
> Hello,
>
> there seems to be large performance regression starting in sed 4.5.
> I've done most of the testing on sed 4.4 and 4.5 since this seems to
> be the point where it was introduced, but it is present in 4.9 too.
>
> Command I'm using:
>
>  sed -nf program.sed input > /tmp/out
>
> program.sed should be in the attachment, the input file is 355MB
> large, so I am attaching only a head -n100 of the input file (can
> share the rest somehow if needed). When running with sed 4.4 the run
> ends in roughly a minute (with the full input file), however with the
> newer versions, sed runs for several hours (~4h). Both versions were
> built/run on the same machine. I am also attaching a gprof profiles of
> the 4.4 and 4.5 runs.
>
> Thanks,
> Jakub