Re: git-svnimport failed and now git-repack hates me

"Randal L. Schwartz" [off-list ref] wrote:

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"Eric" == Eric Wong [off-list ref] writes:

Eric> Part of it is Perl, which (as far as I know) never frees allocated
Eric> memory back to the OS (although Perl can reuse the allocated memory for
Eric> other things).

It does on Linux, of all things.  That's because Linux has a smarter
malloc/free that uses mmap(2) for the large chunks.  On Linux, Perl memory
size can apparently grow and shrink nicely.  The "old school" advice about
Perl comes from sbrk(2)-driven malloc/free.

Try:

        $x[1e6] = "0";
        sleep 10; # do a ps here
        @x = ();
        sleep 30; # do a ps here

and watch the process on Linux.  If I'm right, this should show a large
process,  then a smaller one.

Nope, not happening to me.  I'm using Perl 5.8.8-7 and glibc 2.3.6.ds1-8
on a Debian Etch machine.  The kernel is a vanilla 2.6.18.1 from
kernel.org.

strace shows an mmap2 call, but no corresponding mumap.  I've added a
sleep loop to the end of the above program and had it print
something every 10 seconds; but so far, there's still no munmap.

while (1) {
        print "hi\n" if ((time % 10) == 0);
	sleep 1;
}

Trying to allocate a bigger chunk (1e7) doesn't show anything different,
either.  I've also conducted similar experiments with Ruby in the past
and noticed the same things...

-- 
Eric Wong