Well, as you can see from the ensuing discussion my first post was really overdramatizing what I had heard and I don't know as much about the topic as I should

Obviously the ~300x penalty for using ithreads only comes into play with heavy sharing of variables, which I was wrongly assuming to be happening with the tied hashes of MLDBM.

Instead in your case (with the disk based data) there are a lot of io waits that can be used by other threads/processes to continue and this is ideal for parallelization. So I would be very interested to know whether your speedup really comes from the quad-core. If I'm correct with my guess, your program with 4 threads would run nearly as fast or even faster with one core than with four (isn't there a way to turn of cores in the BIOS or somewhere?). And if that really is the case, there might be another speedup possible with Marcs Coro package.

In reply to Re^5: If I am tied to a db and I join a thread, program chrashes by jethro
in thread If I am tied to a db and I join a thread, program chrashes by lance0r

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