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Here is a little script for linux only that can help to understand what happens to memory:

our @test; print "nothing : Size = ".size()."\n"; push @test, rand for (1..100000); print "push : Size = ".size()."\n"; #undef @test; @test = (); print "deleted : Size = ".size()."\n"; sub size { open DATA, "< /proc/$$/status" or die "Unable to read data : $!\n"; local $/; <DATA> =~ m/^VmSize:\s+(.*?)$/m; return $1; }

If I use @test = ();, output is
nothing : Size = 2988 kB push : Size = 5492 kB deleted : Size = 5492 kB

and with undef @test;
nothing : Size = 2988 kB push : Size = 5488 kB deleted : Size = 4976 kB

Of course, this example is OS dependant. But you can notice that the first solution does not free any OS memory at all. As FatVamp said, Perl can then reuse the memory. It can be noticed that a few more memory is freed when using undef, but not all that was used.

HTH

--
zejames

In reply to Re: Does undef free ram? by zejames
in thread Does undef free ram? by Xxaxx

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