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Re^2: Blessing with unknown classnames

by choroba (Cardinal)
on Apr 01, 2021 at 23:44 UTC ( [id://11130695]=note: print w/replies, xml ) Need Help??


in reply to Re: Blessing with unknown classnames (updated x 2)
in thread Blessing with unknown classnames

Run
perl -we 'bless {}, "A$_" for 1 .. 2000000'
and what your memory meter.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

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Re^3: Blessing with unknown classnames
by Discipulus (Canon) on Apr 02, 2021 at 07:45 UTC
    Nice,

    on my windows 10 box each package seems to eat ~1k of memory:

    perl -we "sub mem{system qq(tasklist /FI \"PID eq $$\"|findstr perl)}; + mem();bless {}, qq(A$_) for 1 .. 1000000;mem()" perl.exe 29356 Console 1 6 +.616 K perl.exe 29356 Console 1 1.353 +.656 K

    and quite the same on my Linux box:

    perl -we 'sub mem{system qq(cat /proc/$$/status | grep ^VmSize)}; mem( +);bless {}, qq(A$_) for 1 .. 1000000;mem()' VmSize: 23768 kB VmSize: 1234168 kB

    Obviously the package is empty..

    perl -MDevel::Symdump -e "bless {},'notexisting';print Devel::Symdump- +>new('noexisting')->as_string" arrays functions hashes ios packages scalars unknowns

    ..holding just the AUTOLOAD

    use strict; use warnings; my %before = %main::; bless {},'nonexistent'; my %after = %main::; foreach my $symbol (sort keys %after) { next if exists $before{$symbol}; local *myglob = $after{$symbol}; if ( defined *myglob{HASH} ) { my %val = %{ *myglob{HASH} }; print "HASH \%$symbol = ( "; while( my ($key, $val) = each %val ) { print "$key=>'$val', "; } print ")\n" ; } } __END__ HASH %nonexistent:: = ( AUTOLOAD=>'*nonexistent::AUTOLOAD', )

    ..but: For various obscure reasons, typeglobs are always created with a Null SV in the SCALAR slot.

    L*

    There are no rules, there are no thumbs..
    Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.
      It doesn't matter if the package is empty, a STASH was created to hold the symbols.

      And the initial overhead for a hash is profound, even if it's empty. Like I said several hundreds of bytes.

      Furthermore do I remember someone explaining that packages which become classes receive further optimization. In order to speed up method lookup (IIRC), but I don't really know the details..

      I'm not aware of any application which tries to generate a massive amount of pseudo packages, I'm just saying it might not be the best idea to create many global data structures which are never destroyed.

      And if you only generate a small number, take care about controlling the namespace, because they are global.

      Fun fact: As a side effect of my experiments I was even able to block a package name in a way that any further package blocked_name; would globally fail.

      Like: "Hey I hate Moose, if you use my module in your project you won't be able to ever use Moose later!" ;-)

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery

      > ..holding just the AUTOLOAD

      hmm interesting ... it's only the scalar $AUTOLOAD which is created and not any sub &AUTOLOAD

      And the value is undef

      I'd say that's only a random side-effect (probably bug), there is no use of $AUTOLOAD without &AUTOLOAD

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery

Re^3: Blessing with unknown classnames
by LanX (Saint) on Apr 03, 2021 at 01:46 UTC
Re^3: Blessing with unknown classnames
by LanX (Saint) on Apr 02, 2021 at 00:04 UTC

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