Regex profiler

phizel has asked for the wisdom of the Perl Monks concerning the following question:

Does a profiler exist for regular expressions? The only thing I could find was re's debug mode, but the output isn't very intuitive. I am imagining something like Devel::NYTProf with flame graphs indicating which sections of a regex need optimizing. Take the common whitespace trimming example s/^\s+|\s+$//g; it turns out to sub-optimal because the alternation negates the anchor optimization. Since I can't make heads or tails of re's debug mode output, the only tool in my toolbox for diagnosing regexen is to compare runtimes with Benchmark. Since regular expressions are a feature of many other languages, a better solution might even exist outside of perl.

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Re: Regex profiler by Corion (Patriarch) on Jan 18, 2026 at 07:25 UTC
Regexp::Debugger can create a heatmap of a match.	[reply]
Re: Regex profiler by choroba (Cardinal) on Jan 17, 2026 at 20:16 UTC
> a better solution might even exist outside of perl. Note that other languages might have similar regex syntax to Perl, but the implementation is definitely different, so profiling/benchmarking it doesn't really help if you're going to use the regex in Perl. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re: Regex profiler by LanX (Saint) on Jan 19, 2026 at 13:06 UTC
Depending on what you mean by "profiling" you can inject Perl `(?{code})` snippets into your regex to record the current time. (IMHO that's the most likely approach a third party profiler would take) But please be aware that you might get a Heisenbug situation then, because your snippet was hindering some of the many internal heuristics or optimizations. Looking into `re` `debug` mode before and after those injections is always a good approach. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]