Magic Banana is perplexed by my experience with grep's memory usage:
> Your experience with grep is weird. As far as I understand, grep's memory
requirement
> do not depend on the number of lines (which could be infinite). It
processes one single
> line, outputs it if and only if it matches the regular expression, then
forgets about
> it to process the subsequent line and so on.
My example had a pattern file of 7700 rows and a target 0f 2200 rows; the
grep script
searching that combination saturated both 7.7 GB of Ram and 18 GB of swap.
I divided the 7700 rows into eight pieces of 1000 rows each (except the last
one of 700
rows). Those eight grep scripts took about 20 seconds each to finish without
taxing
either form of memory.
George Langford
