https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #1 from Jack Stouffer <jack@jackstouffer.com> ---
Introduced here: https://github.com/dlang/phobos/pull/4995

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #2 from Jack Stouffer <jack@jackstouffer.com> ---
Bad news: I see a similar performance decrease for run-time regex as well.

# 2.073.0
$ dmd -O -inline -release test2.d && cat input5000000.txt | time ./test2
./test2  4.44s user 0.09s system 98% cpu 4.591 total

# 2.072.2
~/digger/result/bin/dmd -O -inline -release test2.d && cat input5000000.txt |
time ./test2
./test2  3.20s user 0.09s system 98% cpu 3.344 total

I consistently get around a second and a half longer run time with 2.073.

Code

import std.algorithm;
import std.array;
import std.range;
import std.regex;
import std.stdio;
import std.typecons;
import std.utf;

static variants = [
    "agggtaaa|tttaccct",
    "[cgt]gggtaaa|tttaccc[acg]",
    "a[act]ggtaaa|tttacc[agt]t",
    "ag[act]gtaaa|tttac[agt]ct",
    "agg[act]taaa|ttta[agt]cct",
    "aggg[acg]aaa|ttt[cgt]ccct",
    "agggt[cgt]aa|tt[acg]accct",
    "agggta[cgt]a|t[acg]taccct",
    "agggtaa[cgt]|[acg]ttaccct",
];

void main()
{
    auto app = appender!string;
    app.reserve(5_000_000);
    app.put(stdin
        .byLineCopy(KeepTerminator.yes)
        .joiner
        .byChar);

    auto seq = app.data;

    auto regexLineFeeds = regex(">.*\n|\n");
    seq = seq.replaceAll(regexLineFeeds, "");

    foreach (pattern; variants)
    {
        writeln(pattern, " ", seq.matchAll(pattern).walkLength);
    }
}

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https://issues.dlang.org/show_bug.cgi?id=17161

Dmitry Olshansky <dmitry.olsh@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dmitry.olsh@gmail.com

--- Comment #3 from Dmitry Olshansky <dmitry.olsh@gmail.com> ---
(In reply to Jack Stouffer from comment #2)
> Bad news: I see a similar performance decrease for run-time regex as well.
> 
> # 2.073.0
> $ dmd -O -inline -release test2.d && cat input5000000.txt | time ./test2
> ./test2  4.44s user 0.09s system 98% cpu 4.591 total
> 
> # 2.072.2
> ~/digger/result/bin/dmd -O -inline -release test2.d && cat input5000000.txt
> | time ./test2
> ./test2  3.20s user 0.09s system 98% cpu 3.344 total
> 
> I consistently get around a second and a half longer run time with 2.073.
> 

This is interesting find, thanks for sharing!

Will investigate the R-T issue, C-T is (sadly) to be expected.

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #4 from Dmitry Olshansky <dmitry.olsh@gmail.com> ---
(In reply to Dmitry Olshansky from comment #3)
> (In reply to Jack Stouffer from comment #2)
> > Bad news: I see a similar performance decrease for run-time regex as well.
> > 
> > # 2.073.0
> > $ dmd -O -inline -release test2.d && cat input5000000.txt | time ./test2
> > ./test2  4.44s user 0.09s system 98% cpu 4.591 total
> > 
> > # 2.072.2
> > ~/digger/result/bin/dmd -O -inline -release test2.d && cat input5000000.txt
> > | time ./test2
> > ./test2  3.20s user 0.09s system 98% cpu 3.344 total
> > 
> > I consistently get around a second and a half longer run time with 2.073.
> > 
> 
> This is interesting find, thanks for sharing!
> 
> Will investigate the R-T issue, C-T is (sadly) to be expected.

Mystery solved - in R-T version regex is parsed at C-T (because of static) therefore the disabling of Kickstart affect it too.

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #5 from Jack Stouffer <jack@jackstouffer.com> ---
(In reply to Dmitry Olshansky from comment #3)
> Will investigate the R-T issue, C-T is (sadly) to be expected.

Is there anyway to revert the CT regex to 2.072 behavior? It would be great if a performance regression of this size on one of the selling points of D could be fixed immediately.

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #6 from github-bugzilla@puremagic.com ---
Commits pushed to stable at https://github.com/dlang/phobos

https://github.com/dlang/phobos/commit/5a2491a847beb035b37ee2a270029499065b1919 Fix Issue 17161 - Revert all changes to std.regex from 2.072.2 onwards

https://github.com/dlang/phobos/commit/c4f4cfeda6ba60e2df6eef05bc1f8946982e9a99 Merge pull request #5113 from JackStouffer/revert-regex

Issue 17161 - [REG 2.072.2] Massive Regex Slowdown

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https://issues.dlang.org/show_bug.cgi?id=17161

github-bugzilla@puremagic.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #7 from github-bugzilla@puremagic.com ---
Commits pushed to master at https://github.com/dlang/phobos

https://github.com/dlang/phobos/commit/5a2491a847beb035b37ee2a270029499065b1919 Fix Issue 17161 - Revert all changes to std.regex from 2.072.2 onwards

https://github.com/dlang/phobos/commit/c4f4cfeda6ba60e2df6eef05bc1f8946982e9a99 Merge pull request #5113 from JackStouffer/revert-regex

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https://issues.dlang.org/show_bug.cgi?id=17161

--- Comment #8 from github-bugzilla@puremagic.com ---
Commits pushed to newCTFE at https://github.com/dlang/phobos

https://github.com/dlang/phobos/commit/5a2491a847beb035b37ee2a270029499065b1919 Fix Issue 17161 - Revert all changes to std.regex from 2.072.2 onwards

https://github.com/dlang/phobos/commit/c4f4cfeda6ba60e2df6eef05bc1f8946982e9a99 Merge pull request #5113 from JackStouffer/revert-regex

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