Performance issues in running .NET Core APIs in Azure App Services for Linux

1
votes

I tried porting some of my Web APIs built on .NET Core 3.1 to Azure App Services (on Linux). Earlier all these APIs were hosted in Azure App Services (on Windows), but I wanted to port to them to a Linux Environment, due to the huge cost benefits associated with them.

However after porting them and running some of the performance suites I found some serious performance difference between Linux and Windows App Service. I was expecting that performance in Linux App Service would either improve or remain the same, but to my dismay the performance actually degraded. Here are some of the results:

+-----------------------------------------------+-----------+--------+---------+
| Operation                                     | User Load | Linux  | Windows |
+-----------------------------------------------+-----------+--------+---------+
| Cosmos DB Read                                | 50        | 600 ms | 60 ms   |
+-----------------------------------------------+-----------+--------+---------+
| Simple Ping                                   | 50        | 30 ms  | 20 ms   |
+-----------------------------------------------+-----------+--------+---------+
| 15 parallel calls to Azure Feature Management | 50        | 510 ms | 160 ms  |
+-----------------------------------------------+-----------+--------+---------+

What is causing this performance degradation in Linux? Is it a .NET Core thing, where performance is better in Windows compared to Linux. If so, is this something that would get addresses in .NET 5 or other subsequent releases?

1
linuxazureazure-web-app-serviceazure-app-service-plans
I find the blog about testing performance. The test results seem to be the opposite of what you said. – Jason Pan
If possible, can you share your testing process and code? – Jason Pan

1 Answers

2
votes

For CosmosDB at least, there is a documented performance preference for Windows when using the .NET SDK:

We recommend Windows 64-bit host processing for improved performance. The SQL SDK includes a native ServiceInterop.dll to parse and optimize queries locally. ServiceInterop.dll is supported only on the Windows x64 platform. For Linux and other unsupported platforms where ServiceInterop.dll isn't available, an additional network call is made to the gateway to get the optimized query.