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Subject:	Is there anyway to reduce cygwin perl's String memory usage?
Date:	Wed, 30 Dec 2009 03:13:01 -0500
Message-ID:	<FF6036EF5FD259479DEA1D09B2BB485E043027F9@mail1.sangate.com>
From:	"Zhao, Dong" <dzhao AT sepaton DOT com>
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Cc:	"Zhang, Eric" <ezhang AT sepaton DOT com>
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Dear All:
Recently our Perl project run into the "Out of memory" issue on Windows Cyg=
win, while it works well on Linux, after optimized the code ,it still didn'=
t work on Windows Cygwin perl(Because we do a lot of analysis bases on stri=
ng arrays and hashes) . We found the reason is Cygwin perl uses much more m=
emory than Linux perl or Windows As perl.
We did a lot searches over the internet but didn't found a solution yet.
I did tune the =A0"heap_chunk_in_mb" flag to "2048" =A0in registry "Softwar=
e/Cygnus Solutions/Cygwin/". But our Perl script still exhausted over 1GB m=
emory and crashes on Cygwin perl.

Then I compared the memory usage difference between Cygwin perl, Windows AS=
 perl, and Linux Perl use this simple script:

=A0=A0=A0 my @array =3D ();
=A0=A0=A0 my $str =3D "A" x 1024;=A0 #A string with 1024 len
=A0=A0=A0 for(my $i=3D0;$i<100*1024;$i++){
=A0=A0=A0=A0=A0=A0=A0 push @array,$str;
=A0=A0=A0 }
=A0=A0=A0 <STDIN>; #No we can take a look at memory.

I expected it to use about 100M memory for all platforms. But Windows cygwi=
n perl use about 200M, while AS perl and Linux perl only used 100M.
Our current cygwin perl version is v5.10.0. And cygwin version is 1.7.1.
I also tried the latest cygwin perl version : v5.10.1. But still the same r=
esult.

Can anyone explain to me?=A0 It there a simple way to reduce the cygwin per=
l's memory usage(Set some flag?Or recomple cygwin perl code)
Thanks for any answer!

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