ThreadQueueSample

Showcase for aspnet core Threadpool Starvation

Prerequisites

Install dotnet-counters

https://github.com/dotnet/diagnostics/blob/master/documentation/dotnet-counters-instructions.

Install a load Testing Tool

To test this use a load test tool. For example https://github.com/codesenberg/bombardier go get -u github.com/codesenberg/bombardier

Start the webserver

dotnet run -c Release

Run some load tests

500ms with clean async await

bombardier -k -c 128 -n 50000 https://localhost:5001/blocking/non500ms

50ms with clean async await

bombardier -k -c 128 -n 50000 https://localhost:5001/blocking/non50ms

Run the bad Requests which block 500ms

bombardier -k -c 128 -n 50000 https://localhost:5001/blocking/block500ms

Depending on your hardware you have to adjust the -c parameter. My Setup is a Ryzen 3950. So the default ThreadPool.GetMinThreads(); is 32.

Observations

As expected the server as a high throughput as long you don't have blocking requests.

• Only GET /blocking/non500ms ==> ~250rps
• Only GET /blocking/non50ms ==> ~2500rps
• Mix of non50ms and non500ms ==> Same Numbers
• Mixing the block500ms into the mix ==> ThreadPool Starvation warnings and even crashing bombardier with timeouts