What is the optimum value (or range) for MaxWorkerThreads sitecore setting?

Question

I believe that the default value for the MaxWorkerThreads is 20. In order to increase the number of concurrent user requests that can be processed, this needs to be increased from its default value.

I was wondering what is the optimum range for this setting? Does that range change on number of cores that are available? Also, is there a particular value above which increasing the number of threads won't really matter?

I read this post https://forums.asp.net/t/1299590.aspx?Why+maxWorkerThreads+100+and+minFreeThreads+88+is+suggested+ about increasing threads in ASP.net and it sounds like they point towards it being 100. Does that hold good here?

Answer 1

I once had to tune a server with Sitecore because we did get a lot of requests and couldn't add more servers (for several reasons). I used this blog as a resource, and although it is a few years old it helped me get a significant amount of extra requests handled on the same infrastructure and code.

To answer to the MaxWorkerThreads, I did indeed put that at 100. But I also tweaked other settings like the maxconnection, minWorkerThreads and minFreeThreads.

Note that some of those settings are automatically multiplied by the number of CPUs and some are not.

When you want to tweak these settings, you could follow the basic recommendations as in the blog, but it's better to read the explanation and decide what to do based on your specific project. Example: we had lots of requests from our code to an external webservice - so we added the address of that service in the maxconnections settings allowing the application to have more connections simultaneously to the service.

One more advice: monitor your application to see if you actually need this. Can your server handle more requests/threads/...? And do it again after you made changes. There are several counters available to see what your IIS is doing (not only CPU, but also requests handled/queued/... and so on).