I did an experiment a while ago and found that string concatenation in a loop was Ο(n²) in rakudo. I asked about it on irc and jnthn explained to me that this was expected because strings are immutable (and therefore wasn't worth RTing): https://irclog.perlgeek.de/perl6/2015-12-15#i_11720228
(some encoding issue causes Ο(n²) to have a bunch of Ãs in it) On Fri, Jul 21, 2017 at 6:39 AM Ron Schmidt <perl6-bugs-follo...@perl.org> wrote: > # New Ticket Created by Ron Schmidt > # Please include the string: [perl #131774] > # in the subject line of all future correspondence about this issue. > # <URL: https://rt.perl.org/Ticket/Display.html?id=131774 > > > > From IRC: > > https://irclog.perlgeek.de/perl6-dev/2017-07-19#i_14893012 > > https://irclog.perlgeek.de/perl6/2017-07-20#i_14899215 > > Code example: > > for (50_000, 75_000) -> $limit {my $x; my $y = "x" x 100; $x ~= $y for > (1..$limit); say "$limit: ", now - ENTER now} > > Gets a MoarVM memory panic from the eval bot for 75_000 constructing a > 7.5 Meg string. According to valgrind 50_000 was allocating 10GB of > memory. At a concat count of 150_000 Perl 5 finishes in hundredths of a > second where p6 takes around a minute and the growth in time with p6 is > clearly worse than linear. "blead" updates as of July 20 include some > improvements and timotimo on IRC mentioned that he is working on others. >
