Guide: IIS Thread pool optimization

We’ve just released our new IIS Threading guide, which explains how the IIS thread pool works and how it affects your website performance.

It turns out that many people don’t have a clear sense of how the IIS thread pool relates to hangs and slowdowns in their website.

So, we took the opportunity to clear things up, and explain how IIS thread pool exhaustion or thread starvation actually affects IIS site performance.

This includes:

  1. 503 Queue Full errors, or application pool queue buildup
  2. Reduced RPS, especially for high performance websites

We also explain how most traditional hangs and slow loads are NOT caused by IIS threadpool issues, but instead the application-specific thread pools like the CLR thread pool, or the Classic ASP thread pool.

Monitoring IIS thread performance

We also show a simple way to monitor IIS counters to detect IIS pool issues.

If you have LeanSentry installed on the server, you can get a lot deeper into actually diagnosing most thread pool issues down to code (part of our application pool failure diagnostics). We’ll cover this well.

LeanSentry diagnosing IIS thread pool issues causing 503 queue full errors
LeanSentry diagnosing an 503 queue full incident down to code causing CPU overload, which is then causing IIS thread delays.

Optimizing the thread pool

In the guide, we dig into the specific causes of threading issues, that actually happen. This is based on monitoring 30K+ IIS websites with LeanSentry in the last decade.

Surprisingly, there are only a couple causes of thread pool issues that matter.

We’ll cover each one, and how to configure the IIS threadpool to resolve them.

For the juicy details, head over to the thread pool guide.

Guide: Maximum IIS application pool availability

Building on our last week’s Reset, Restart, Recycle IIS guide, this week we are digging deeper into improving IIS application pool availability.

Head over to How to maximize IIS application pool availability to see how you can tweak your IIS websites to:

  1. Start in 100%-warm state, for best cold-start performance (even after a production restart or recycle)
  2. Have zero startup delay (despite the warmup we just mentioned)

Yes, basically you CAN have your cake and eat it too.

Meaning your website is always warm, and can recycle without the users feeling it. This requires getting a lot of pieces right, and guide shows you exactly how to do that.

Best of all, it requires ZERO code.

Configure it all instantly with the ConfigureWarmup tool

We have a tool that will automatically configure the warmup configuration for your website. We’ll be releasing this tool shortly, but if you want it now, be sure to sign up for the Guide newsletter early access. This will allow you to get all our guides, and tools, before they are publicly released online.