This repository contains ASP.NET Core projects that intentionally have performance-impacting bugs that can be used to demo performance diagnostic tools like PerfCollect and PerfView.
- Blocking Calls demonstrates the effects of waiting synchronously for long-running operations like database access or remote service calls. This demo runs quickly when run just once (even the slow path), but will slow down over time when run under load as the thread pool is exchausted and new threads aren't added quickly enough to keep up with incoming load. The fast endpoint addresses this issue by making request processing async.
- Inefficient Data Access demonstrates the effects of interacting with remote services and databases inefficiently ("chatty" communication). The slow path in this demo makes repeated calls to the database while the fast path makes just two queries. The performance impact is immediately apparent.
- Large object allocations demonstrates the effects of
allocating and cleaning up many large objects. The slow path will run quickly
when run only once. Under load, however, performance will be inconsistent -
fast at first, but then periodically becoming much slower as request
processing is paused for gen 2 garbage collections. The fast path avoids this
problem by renting shared
byte[]s from anArrayPoolinstead of repeatedly allocating and freeing large arrays. - Combined test combines all three other problems in one (very buggy) demo application. Instead of the /fast and /slow endpoints exposed by the other web APIs, this one has four endpoints (/test1, /test2, /test3, and /test4) demonstrating different stages of correcting the various performance problems. The first API (/test1) exhibits all three problems whereas /test4 has them all corrected.
The PerfTests folder contains trivial web tests and load tests
that can be used to stress the demo apps. TestAPISlow and TestAPIFast
target the slow and fast endpoints, respectively, of the first three
scenarios. TestAPI is meant to be used with the combined demo, but it is
necessary to update TestAPI.webtest to point at the particular endpoint
(/test1, /test2, /test3, or /test4) that you want to exercise.
Since the perf tests only hit a single endpoint each, you can also test with simpler performance tools like Apache Bench, Siege, or any number of other load testing tools.
All projects can be built and launched with the dotnet CLI
(dotnet run).
All of the scenarios except for large object allocations depend on the AdeventureWorks sample database. To setup the database, either create an Azure SQL database (pre-populating with AdventureWorks data is an option in the Azure portal while creating the database) or setup the database locally using the AdventureWorks Installation instructions.