Threading

If used poorly, threading can consume a lot of CPU cycles needlessly. If your code is multi-threaded, consider the following ways to reduce threading overhead:

• If you use threads to wait for off-box resources such as databases or web services, consider using asynchronous requests instead. These are described in Chapter 6,

• Do not create your own threads. This is very expensive. Instead, use ThreadPool.QueueUserWorkItem to get a thread from the thread pool.

• Do not use threads for CPU-intensive tasks. If you have four CPUs, there is no sense in having more than four CPU-intensive tasks.

• Thread switches are expensive. Try to reduce the number of threads running simultaneously.

To get more information about the threads currently running, check these counters in perfmon.

Category: Thread
% Processor Time	Shows for each thread what percentage of processor time it is taking.
Context Switches/sec	Shows for each thread the rate of context switches per second.