At some point you are right, contention becomes an issue. However I have found as a practical matter on commodity hardware that that point isn't hit until you have 5-10 parallel processes reading.

Of course I last looked into this a while ago. The figure is undoubtably different today. Benchmark for your purposes.

But my point remains. I/O bound jobs are excellent candidates for parallelization. Due to various sources of latency, one process generally comes nowhere close to maxing out I/O. If you don't have to worry about getting in other people's way, it almost always makes sense to have multiple parallel processes.

In reply to Re^5: Algorithm advice sought for seaching through GB's of text (email) files by tilly
in thread Algorithm advice sought for seaching through GB's of text (email) files by chargrill

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