Dear Perlmonks,

I am writing to you to seek some advice on how to optimize a script I wrote. I will first describe the situation, and then present the possible solutions.

The size of the input file is about 50mb; each line contains a string which is built like this:

abcd\tabcd

where \t is a tab seperating the two blocks.

As for now, I read the whole file line by line and search $_ for a given string. If found, I push the second block into an array. To do so, I match every line against the regular expression ^(.*)\t(.*)$.

I am experiencing serious performance issues. It takes me between 5 and 10 seconds to have the final array.

I have read a bit and found out that there are plenty of ways to program this script differently. Which would be the best solution?

a) read the whole file into an array and then parse the array?

b) read the file line by line, as I do now?

c) a friend also told me the reg exp was inefficient. He said I would gain some speed by replacing the reg exp with the index and substring functions. True?

d) create an index of the file? I'm not really sure how to tackle this.

So dear Perlmonks, thanks in advance for your advice.

Larry

In reply to performance issues by perlcat

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