Re: write hash to disk after memory limit

I'm not sure if I understand your question completely...

... but I once had a problem with a giant hash constantly swapping and solved it by splitting up the hash into a two tier HoH.

If you can organize the upper tier roughly according to the timeline of your process, your system will only swap the necessary lower hashes on demand.

I already described this here, will update the link after I found it.

HTH! :)

update

see Re: Small Hash a Gateway to Large Hash?

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}

PS: Je suis Charlie!

Comment on Re: write hash to disk after memory limit

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Re^2: write hash to disk after memory limit by hailholyghost (Novice) on Mar 13, 2015 at 13:30 UTC
thanks a lot, I've been using hash-hash-array-array in order to keep memory use down. I think array access is also faster than hash, so I did this: foreach my $rat (@directories) { print "Reading Merged_99$rat/bs_seeker-CG.tab ...\n"; open(FH,"<Merged_99$rat/bs_seeker-CG.tab") or die "cannot read M +erged_99$rat/bs_seeker-CG.tab: $!"; while (<FH>) { if (/M/) { next; } elsif ((/^chr(\S+)\s+(\d+)\s+\d+\s+(\d)\.(\d+)\s+(\d+)/) && + ($1 ~~ @CHROMOSOMES) && ($5 >= $MINIMUM_COVERAGE)) { #chromosome $1, methylated C $2, percent $3.$4 and coverage $5 $DATA{$1}{$2}[$set][$replicate] = "$3.$4"; } elsif ((/^chr(\S+)\s+(\d+)\s+\d+\s+(\d)\s+(\d+)/) && ($1 ~~ + @CHROMOSOMES) && ($4 >= $MINIMUM_COVERAGE)) { $DATA{$1}{$2}[$set][$replicate] = $3; } } close FH; $replicate++; } [download]	[reply] [d/l]
Re^3: write hash to disk after memory limit by LanX (Saint) on Mar 13, 2015 at 13:41 UTC
As I said, better > > organize the upper tier roughly according to the timeline of your process No idea where $set comes from but $replicate could be such a top tier. so `$data[$set][$replicate]{$1}{$2}` should have far less memory swapping problems (AFAIS). (BTW better reserve uppercase var-names to perl buit-ins) If this structure doesn't fit into your future plans, you most likely want to use a DB anyway. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)} PS: Je suis Charlie!	[reply] [d/l]
Re^3: write hash to disk after memory limit by Jenda (Abbot) on Mar 14, 2015 at 00:59 UTC
Do you later use the value as a string or as a number? If you use it as a number, I believe you could save quite a bit of memory by forcing a conversion before storing the data. The way you do it, you end up with a scalar containing both the string and (as soon as you use the number for the first time) the number. `... $DATA{$1}{$2}[$set][$replicate] = 0 + "$3.$4"; } elsif ((/^chr(\S+)\s+(\d+)\s+\d+\s+(\d)\s+(\d+)/) && ($1 ~~ + @CHROMOSOMES) && ($ +4 >= $MINIMUM_COVERAGE)) { $DATA{$1}{$2}[$set][$replicate] = 0 + $3; ...` [download] Jenda Enoch was right! Enjoy the last years of Rome.	[reply] [d/l]


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