There are so many performance problems in this code that it's kind of hard to know where to begin! Here's a few that jump out right away:
- Don't open file 2 for each line of file 1 and read through every line! If there are 1 million lines in file 1 and 500 thousand lines in file 2 then you'll read 500 billion lines from file 2! Instead read file 2 once and re-use the hash for each lookup.
- Don't re-sort all the keys from file 1 everytime you read a line from file 1. (UPDATE: Looking again I see that %fets is actually local to the while(). Why are you using a hash at all here? Why are you calling sort() when only one key is present?)
- You may not have enough memory to actually hold all of file 2 in memory at once. If you don't you'll run into swap, which will be slow no matter what you do. You can fix this by storing the hash in a database file via DB_File or something similar.
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
Outside of code tags, you may need to use entities for some characters:
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||