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2 seconds to read it; 1/2 second to process it; 4 seconds to write it; and only 510MB memory used in the process!

That's efficient!

Not really, from a memory standpoint. You could do much better with a standard loop that reads to a small buffer and writes to the output file in a loop.

(Not to mention that you seem to have really fast disks (SSDs?). Haven't met a HDD yet that could read faster than 150 MB/s or write faster than 100 MB/s.)

open my $in, '<', 'input.txt' or die; open my $out, '>', 'output.txt' or die; my $buf; while (read $in, $buf, 4096) { $buf =~ tr/\t/ /; print $out $buf; } close $_ for ($in, $out);

But, this has a large potential to slow down the loop to around 10 MB/s because of properties of seeking media, and OS algorithms on read-ahead and flushing that never quite give that good performance [1]. Still a helluva lot better than the OS swapping you out because it can't fit the 500 MB into memory.

[1] I have never seen an OS successfully avoid doing reading and writing in parallel (= sub-optimal) for cat largefile > otherfile


In reply to Re^2: Windows 7 Remove Tabs Out of Memory by Anonymous Monk
in thread Windows 7 Remove Tabs Out of Memory by tallums

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