Newly created threads using Task.Factory.StartNew starts very slowly

Question

In an WPF/c# application that uses around 50-200 of short living worker-threads created by Task.Factory.StartNew it takes from 1 to 10 seconds before the newly created thread starts executing.

What is the reason for this very slow thread execution start?

Update: The delay is excatly 500 msec

Answer 1

Found out that the thread pool can be unwilling to start more than one new thread every 500 msec when the number of thread pool threads used are over a specific value. However increasing MinThreads using ThreadPool.SetMinThreads - even though it is not recommended - to 100 enables me to create 100 threads without the 500 msec delay.

Here's what helped me:

• http://alexpinsker.blogspot.com/2009/06/threadpool.html

• http://msdn.microsoft.com/en-us/library/system.threading.threadpool.setminthreads%28v=vs.100%29.aspx

• https://stackoverflow.com/a/13186389/600559

Edit:

Here's what I ended doing in App.xaml.cs (in the constructor):

// Get thread pool information
int workerThreadsMin, completionPortThreadsMin;
ThreadPool.GetMinThreads(out workerThreadsMin, out completionPortThreadsMin);
int workerThreadsMax, completionPortThreadsMax;
ThreadPool.GetMaxThreads(out workerThreadsMax, out completionPortThreadsMax);

// Adjust min threads
ThreadPool.SetMinThreads(workerThreadsMax, completionPortThreadsMin);