I stumbled on a forum posting recently that led me to write the following code:
using System;
using System.Threading;
class Program
{
static void Main()
{
ThreadStart doNothing = delegate { };
ThreadStart createThreads =
delegate
{
for (int i = 0; i < 50; i++)
{
Thread t = new Thread(doNothing);
t.Priority = ThreadPriority.BelowNormal;
t.Start();
}
};
for (int i = 0; i < 2; i++)
{
Thread t = new Thread(createThreads);
t.Start();
}
Console.ReadLine();
}
}
This program behaves badly on a single processor machine, and pegs the CPU at 100% for over two minutes. On a multi processor machine, the program finishes all the threading work in the blink of an eye - only a brief CPU spike.
Strangely, if I remove a single line of code:
t.Priority = ThreadPriority.BelowNormal;
… then the program performs just as well on a single processor machine (only a brief spike - comparable to the MP scenario).
Could it be a bug?