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/9ba26bb4-fc04-46fb-bf26-ad45bb57cfd6n%40googlegroups.com.
