I've done some further testing on the subject: I also added some calculations in the main loop to see what effect they would have on speed. Of course, I also added the same calculations to the single threaded functions. They were simple summary functions, like average, sum, etc. Almost no interaction with the buffers was added, just retrieval of a single field's value.
Single threaded, the calculations added another 4.3 seconds to the processing time (~18%) MultiThreaded, they added 1.8 seconds. CPU usage remained below 100% of one core at all times. Made me check the process affinity. I know the main thread uses way less CPU than DBF reading thread (4 secs vs 22 secs). So I think adding these calculations should have but a minimal impact on threaded execution time. Instead, the execution time increases!!! I'm beginning to think that Python's memory management / functions introduce quite a significant overhead for threading. I think I'll just write this program in one of the compilers today to verify just how stupid I've become. -- http://mail.python.org/mailman/listinfo/python-list
