I have a dual core processor, now let’s say that I want to make a spam bot program, which will spam messages such as “Hey, how are you?”.
My question is, what number of threads would be able to pop up these messages the fastest, running 5 threads or 100 threads botting the messages? (Of course, these numbers aren’t special, just for the example). All of the threads will run in thread-safe.
EDIT: As for the down votes before, I’m not really writing a spambot program, I just mentioned it as an example for my question, sorry for the misunderstanding
The ideal number of threads depends on your hardware (in this case a dual core processor), and on what those threads are doing. If they are CPU intensive, more than 1 thread per core will probably slow things down.
If the threads do some IO, you will see an overall increase in performance by adding threads. The point of diminishing returns depends entirely on the nature of the non-CPU tasks and on the specific hardware.
To find that point, you will have to test various thread totals.
You can design your system to self-tune the number of threads in use. I once designed a system that ran best (most total throughput) when the total CPU load was about 70%. To optimize for that value, I added threads (with a delay between threads) until the CPU was at 70%, +/- 5%. If it went above 80%, I signaled one or more threads to finish their current work and terminate. If it went below 60%, I gradually added threads. Worked like a charm.