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Writing Software for Multicore System

Alec Lee
Ranch Hand

Joined: Jan 28, 2004
Posts: 569
If i want to utilise the multicore CPU as much as possible, is it simply by making my program spawning as much threads as possible? Assuming I can break down my program into parallell running units and it handles thread-safety issue manually.

If yes, then how many threads are optimal? Since I cannot foresee the number of cores the target systems will have.
Steve Luke

Joined: Jan 28, 2003
Posts: 4181

How many threads are optimal? That depends a lot on the program - what it does, and how many processors are available. There is no way to really predict it. The best thing you can do is make your program with a configurable number of Threads (a Thread Pool comes to mind - see ExecutorService for more). Then test the number of Threads that get you the correct performance.

You can also get a bit more detailed, depending on the work that you are doing. You may need to balance threads that 'get' data (producers) and threads that use data (consumers) - or threads that use I/O like disks, or databases, with those that don't. So there is no magic number, you have to code and test to see.

Don't get me started about those stupid light bulbs.
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