Hi, I would like to apologize, but it looks like I had a technical problem in my measurements, and after double-checking it is indeed as all of you wrote: Perl does a very good optimization , and there is no real list creation involved.
Thank you all Yossi -----Original Message----- From: Perl [mailto:perl-boun...@perl.org.il] On Behalf Of Shlomi Fish Sent: Thursday, May 22, 2014 10:28 AM To: Perl in Israel Subject: Re: [Israel.pm] Perl performance optimization question Hi Yossi, On Thu, 22 May 2014 06:27:47 +0000 Yossi Itzkovich <yossi.itzkov...@ecitele.com<mailto:yossi.itzkov...@ecitele.com>> wrote: > Hi, > > Here is a small test that shows the problem (memory consumption of > counting the size of a huge hash, with not-so-small keys) > > ------- > my %hash; > for (my $i=0; $i<5000000;$i++){ > $hash{$i x 100}=$i}; > print "OK\n"; > sleep 20; ### Here the memory is about 3G print (scalar keys > %hash,"\n"); sleep 10 ### here the memory is 3.5 G > ------ > With this program: « #!/usr/bin/perl use strict; use warnings; my %hash; for (my $i=0; $i<2000000;$i++) { $hash{$i x 100}=$i; }; print "OK\n"; my $l = <>; print (scalar keys %hash,"\n"); print "Type enter to exit.\n"; $l = <>; » I don't see a noticeable increase in memory between the two stages. The memory stays mostly the same at the time, according to htop. I tried with both perl-5.18.2-4.mga5 and bleadperl on Mageia Linux x86-64 v5. What is your perl version, the OS+distribution you are using, etc.? Regards, Shlomi Fish > Well, it means the list is being built, and it does consume a lot of memory > (and CPU- but this is not my problem here). In my real application it > crashes, since I have bigger hash/keys, and I am getting "out of memory" > crash. > > Isn't there a better way to get the hash size ? > > Yossi -- ----------------------------------------------------------------- Shlomi Fish http://www.shlomifish.org/ Beginners Site for the Vim text editor - http://vim.begin-site.org/ When Chuck Norris disses your product, it’s not good publicity, even though you can bet he’ll get the name right. — http://www.shlomifish.org/humour/bits/facts/Chuck-Norris/ Please reply to list if it's a mailing list post - http://shlom.in/reply . _______________________________________________ Perl mailing list Perl@perl.org.il<mailto:Perl@perl.org.il> http://mail.perl.org.il/mailman/listinfo/perl
_______________________________________________ Perl mailing list Perl@perl.org.il http://mail.perl.org.il/mailman/listinfo/perl
