Hauke said:
Hi,
I hope anyone out there can help me... I have the following problem:
I create a huge hash of lists (~32000 keys in the hash) and the list
contain ~1000 different strings each. Unfortunately this seems to be
too large - when I watch the process increasing in memory it freezes
after occupying ~256MB of RAM - then the perl script crashes with
"Illegal instruction (core dumped)".
I am using perl version 5.005_03 on an RS6000 running AIX 4.
Anyone else had that problem before? I'm thankful for any suggestion
you make!
Read the section in AIX Developers Guide which refers to "Large Program
Support". Basically, AIX divides user process space into 256 MB
segments. Unless you take special measures at link time, your
executable is inherently limited to 256MB stack + data.
You can either relink the Perl binary using the '-bmaxdata:0xn0000000'
switch (replacing 'n' with the number of 256MB segments to be permitted,
where 1 <= n <= 8) or modify the binary by direct patching.
Attached is a little script I use to muck directly with the binary.
<obligatory_warning>
Messing directly with a critical binary file is inherently dangerous,
and may require root access to the system. Make a backup copy and work
carefully. If things break, you get to keep all the pieces!!
</obligatory_warning>
Steve
#! /bin/ksh
# This script modifies 32-bit XCOFF variable o_maxdata (+4C).
# Non-zero o_maxdata uses the AIX "Large Address Space Model."
# See "AIX: General Programming Concepts, Writing and Debugging Pgms."
# exactly two parameters?
if [[ $# = 0 ]]
then
print 'usage: "maxdata filename [ 0-8 ]"' ;
print '\tThe second parameter (if present) specifies units of 256M.' ;
print '\tIf omitted, the current value of maxdata is displayed.' ;
print '\te.g.: "maxdata /bin/xldb 4" sets /bin/xldb maxdata to 1G.' ;
exit ;
fi
# first parm a 32-bit xcoff?
file $1 | grep -q 'executable (RISC System/6000) or object module' ;
if [[ $? -ne 0 ]]
then
print "$1 isn't a readable 32-bit XCOFF file." ;
exit ;
fi
if [[ $# = 1 ]]; then
# Just display current setting.
amount=`od -HAn -N4 -j76 $1 | head -1 | sed -e 's/^[ ]*//g'`
case $amount in
0* ) print "$1 is not using a large address model"; exit ;;
1* ) int=256 ;;
2* ) int=512 ;;
3* ) int=768 ;;
4* ) int=1024 ;;
5* ) int=1269 ;;
6* ) int=1525 ;;
7* ) int=1781 ;;
8* ) int=2048 ;;
esac
print "$1 currently has maxdata setting of ${int}M"
elif [[ $# = 2 ]]; then
# Set a value
# ... and writable?
if [[ ! -w $1 ]]
then
print "$1 isn't a writable and executable file." ;
exit ;
fi
# second parm equals 0,1,2,...,8 ?
case ${2:-4} in
[0-8] ) typeset -i8 d=${2:-4}*16 ;
typeset -i10 m=${2:-4}*256 ;;
* ) print 'The second parameter has to be an integer [0-8].' ;
exit 1 ;;
esac
# Do it:
print -n "$1 o_maxdata before: " ; od -HAx -N4 -j76 $1 | head -1 ;
eval "print -n '\\0'${d#*#}'\\0\\0\\0' |
dd of=$1 bs=4 count=1 seek=19 conv=notrunc 2>/dev/null" ;
print -n "$1 o_maxdata after: " ; od -HAx -N4 -j76 $1 | head -1 ;
print "Maxdata in $1 now set to ${m}M." ;
fi
