dxxd116 has asked for the wisdom of the Perl Monks concerning the following question:

Hello, Monks:
I have been stuck by this problem for a few days. I have a somehow complicated regular expression inside a child thread in a multi-threaded program. 
my ($mail)=$string=~m/([\w._+-]+@(?:[\w-]+\.)+\w{2,5})(?<!\.jsp|\.asp|
+\.jpg|\.htm)\W/mi;

[download]
When the text to be matched($string) is a little over 1 Megabytes, this regexpression runs forever and never return.
But when I run a single-threaded version of the same program, it works perfectly fine(The regex returns instantly). I am wondering whether there are some settings or limits imposed on the child thread of a multi-threaded program. Could anyone here enlight me on that?
I am running ActiveState Perl 5.10.0 on Windows Platform. Thanks in advance.

Replies are listed 'Best First'.
Re: regular expression hanging inside a child thread
by ikegami (Patriarch) on Apr 17, 2009 at 14:00 UTC

    It's been reported already with no resolution.

    You could force the regexp to be recompiled in each thread for now: 

    # Globals
my $expensive_re_str =
   ''.qr/([\w.+-]+@(?:[\w-]+\.)+\w{2,5})(?<!\.(?:jsp|asp|jpg|htm)\W/i;
my %expensive_re;

# Workaround for perl bug RT#55600
my $expensive_re =
   $expensive_re{$thread_id} ||= qr/$expensive_re_str/;
my ($mail) = $string =~ m/$expensive_re/;

    [download]
[reply]
[d/l]
      That workaround is great! Thank you.
[reply]

Back to Seekers of Perl Wisdom