Do you have benchmarks or only the fprof results? fprof is not a benchmarking tool: comparing fprof results from different code may be misleading. Proper benchmarking is preferrable. I am benchmarking locally and I cannot measure any relevant difference even with the whole version checking removed.
On Thu, Mar 14, 2024 at 6:01 PM Jan Krüger <jan.krue...@gmail.com> wrote: > Thanks a lot. I'm also happy to share our case, and my fprof results, if > that helps. I am very sure that my erlang, and elixir versions match, on > the machine where I've tested this. Replacing Regex.run with an identical > call to :re.run should show the performance improvement I've mentioned. The > regex we've tested this on is: > > ~r/^([a-z][a-z0-9\+\-\.]*):/i > > On Thursday, March 14, 2024 at 5:55:47 PM UTC+1 marcel...@googlemail.com > wrote: > >> I'm the maintainer of RDF.ex library with the RDF.IRI module mentioned in >> the OP. I can confirm that this fix doesn't affect the problem, since we're >> actually not using `URI.parse/1` most of the time (we use it only when >> dealing with relative URIs). Even in this case the `Regex.version/0` call >> in `Regex.safe_run/3` ( >> https://github.com/elixir-lang/elixir/blob/b8fca42e58850b56f65d0fb8a2086f2636141f61/lib/elixir/lib/regex.ex#L533) >> still performs the `:erlang.system_info/0` call. >> >> On Thursday 14 March 2024 at 17:15:40 UTC+1 jan.k...@gmail.com wrote: >> >>> I read the commit, and I don't it fixes what our actual problem was. See >>> my comment above. The problem is the actual call to :re.version, not the >>> recompilation of the regex >>> >>> On Thursday, March 14, 2024 at 4:37:43 PM UTC+1 José Valim wrote: >>> >>>> I have pushed a fix to main. But also note we provide precompiled >>>> Elixir versions per OTP version. Using a matching version will always give >>>> you the best results and that's not only about regexes. :) >>>> >>>> On Thu, Mar 14, 2024 at 2:20 PM Jan Krüger <jan.k...@gmail.com> wrote: >>>> >>>>> I've recently had to work on a code base that parses largish RDF XML >>>>> files. Part of the code base does relatively simple but regular expression >>>>> matches, but since the files are large, quite a lot of Regex.run calls. >>>>> While profiling I've noticed, that there are callouts to >>>>> :erlang.system_info, which fetches the PCRE version BEAM was compiled >>>>> against. >>>>> >>>>> An example regular expression from the code base in question matches >>>>> the schema part of a URL. I've replaced Regex.run with erlang's :re.run >>>>> for >>>>> testing purposes, and at least for this case, there performance gain is >>>>> quite dramatic. >>>>> >>>>> Comparing fprof results: >>>>> >>>>> ``` >>>>> RDF.IRI.scheme/1 1176473 >>>>> 30615.618 2354.355 >>>>> --- >>>>> RDF.IRI.scheme/1 1176473 >>>>> 3531.955 2353.905 >>>>> ``` >>>>> >>>>> I found this thread in the google group, which actually talk about the >>>>> reasoning for fetching the version, and proposes and alternative. >>>>> >>>>> >>>>> https://groups.google.com/g/elixir-lang-core/c/CgFdxIONvGg/m/HN9ryeVXAwAJ?pli=1 >>>>> >>>>> Especially >>>>> >>>>> ``` >>>>> Taking a further look at the code, the issue with recompiling regexes >>>>> on the fly is that it makes executing the regexes more expensive, as we >>>>> need to compute the version on every execution. We could store the version >>>>> in ETS but that would have performance issues. Storing in a >>>>> persistent_term >>>>> would be great, but at the moment we support Erlang/OTP 20+. Thoughts? >>>>> ``` >>>>> >>>>> Since this has a fairly noticeable impact, at least on all tests I've >>>>> run, I wanted to start a discussion, if this could be implemented/improved >>>>> now. >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "elixir-lang-core" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to elixir-lang-co...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/elixir-lang-core/44d498c7-82a4-46d2-89be-7919400e0297n%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/elixir-lang-core/44d498c7-82a4-46d2-89be-7919400e0297n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to elixir-lang-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/507e6bd5-9be9-49a3-b039-45c2173fd509n%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/507e6bd5-9be9-49a3-b039-45c2173fd509n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KCKnDcKKc7uH%2B%2BGB3J9H9%3DdUOZcszdkZvGqJUP6kG2Sg%40mail.gmail.com.
