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Posted by jm on March 29, 2008, 11:12 am
Please log in for more thread options smallpond a écrit :
>> smallpond a écrit :
>>
>>>> Based on the fact that perl contains many memory leaks,
>>>> A universal way to measure how many memory is malloced is required.
>>>> Is there standard way to measure how many memory a process has
>>>> allacated, which run with cygwin perl, active perl, and strawberry perl?
>>>> This should help to localize which code makes memory leaks.
>>> perldoc perlfaq3
>>> See:
>>> How can I make my Perl program take less memory?
>>> How can I free an array or hash so my program shrinks?
>> It is interesting, but it does not seam to solve my substitution issue.
>>
>> However I does not understand this:
>>
>> « Memory allocated to lexicals (i.e. my() variables)
>> cannot be reclaimed or reused even if they go out of scope. It is
>> reserved in case the variables come back into scope. Memory allocated
>> to global variables can be reused (within your program) by using
>> undef()ing and/or delete(). »
>>
>> Aren't my variables local variables?
>> Why aren't they freed when function terminates?
>
>
> sub foo {
> my $v = 5;
> return $v;
> }
>
> In C, once the function terminates $v is gone and a pointer
> to it will fail. In perl this reference is legal and the
> space will not be reclaimed.
>
> In your sample of code above, when you pass a string to a sub,
> perl will make a copy. If you pass a reference it will not.
> This isn't a memory leak in perl, it's a memory leak in your
> program.
As you suggested, I tried to replace scalar by references, but this does
not look like saving memory (might be 10 Mbytes, I mean just the size of
the main variable):
--- results -------------------------
/tmp$ perl essai.pl && echo ok
10000001
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
31679 pts/1 R+ 0:00 0 1022 22977 20996 4.0 perl essai.pl
10000001
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
31679 pts/1 R+ 0:38 0 1022 150157 148372 28.7 perl essai.pl
10000001
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
31679 pts/1 R+ 0:50 0 1022 150157 148372 28.7 perl essai.pl
10000001
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
31679 pts/1 R+ 3:53 0 1022 198997 197212 38.1 perl essai.pl
10000001
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
31679 pts/1 R+ 6:55 0 1022 198997 197212 38.1 perl essai.pl
ok
--- scipt ---------------------------
sub aa($)
{
my ($d) = @_;
$$d =~ s/x(.....)/$1y/g ;
$$d =~ s/x(.....)/$1z/g ;
$$d =~ s/x(.....)/$1a/g ;
$$d =~ s/x(.....)/$1b/g ;
$$d =~ s/x(.....)/$1c/g ;
return $d;
}
sub ab($)
{
my ($d) = @_;
$$d =~ s/a(.....)/$1y/g ;
$$d =~ s/b(.....)/$1z/g ;
$$d =~ s/c(.....)/$1a/g ;
$$d =~ s/y(.....)/$1b/g ;
$$d =~ s/z(.....)/$1c/g ;
return $d;
}
my $s= 'x' x (1000*1000*10) ;
$s .= "\x" ;
my $c = $s;
print length($$c) ."\n" ;
my $v = qx( ps v $$ );
print "$v\n" ;
$c = aa($c);
print length($$c) ."\n" ;
my $v = qx( ps v $$ );
print "$v\n" ;
$c = aa($c);
$c = aa($c);
$c = aa($c);
$c = aa($c);
$c = aa($c);
print length($$c) ."\n" ;
my $v = qx( ps v $$ );
print "$v\n" ;
$c = ab($c);
$c = ab($c);
$c = ab($c);
$c = ab($c);
$c = ab($c);
print length($$c) ."\n" ;
my $v = qx( ps v $$ );
print "$v\n" ;
$c = ab($c);
$c = ab($c);
$c = ab($c);
$c = ab($c);
$c = ab($c);
print length($$c) ."\n" ;
my $v = qx( ps v $$ );
print "$v\n" ;
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