Very bad ADO.NET performance on Linux

[quanmaiepi]

First time reporter - so please let me know if I am missing some important information.

We are investigating a very bad performance characteristics on Linux. It seems it has something to do with the SqlConnection handling.

• .NET 5
• Azure App Service
• Same code runs on Windows very well (same configurations, even with more traffic)
• Affected both databases our app connected to
• Database usage levels are both very low (<10%). We don't see any particularly slow query. In a particular memory dump, we see about 950 threads stuck in this same stacktrace:

00007F5EC7F2A838 00007f65d61873f9 [HelperMethodFrame: 00007f5ec7f2a838] System.Threading.WaitHandle.WaitMultipleIgnoringSyncContext(IntPtr*, Int32, Boolean, Int32)
00007F5EC7F2A980 00007f65667dfa86 System.Threading.WaitHandle.WaitMultiple(System.ReadOnlySpan`1<System.Threading.WaitHandle>, Boolean, Int32)
00007F5EC7F2AA00 00007f6562ee7b96 Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(System.Data.Common.DbConnection, UInt32, Boolean, Boolean, Microsoft.Data.Common.DbConnectionOptions, Microsoft.Data.ProviderBase.DbConnectionInternal ByRef) [/_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/ProviderBase/DbConnectionPool.cs @ 1172]
00007F5EC7F2AA80 00007f65667df0d7 Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(System.Data.Common.DbConnection, System.Threading.Tasks.TaskCompletionSource`1<Microsoft.Data.ProviderBase.DbConnectionInternal>, Microsoft.Data.Common.DbConnectionOptions, Microsoft.Data.ProviderBase.DbConnectionInternal ByRef) [/_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/ProviderBase/DbConnectionPool.cs @ 1142]
00007F5EC7F2AAE0 00007f6562ee553b Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(System.Data.Common.DbConnection, System.Threading.Tasks.TaskCompletionSource`1<Microsoft.Data.ProviderBase.DbConnectionInternal>, Microsoft.Data.Common.DbConnectionOptions, Microsoft.Data.ProviderBase.DbConnectionInternal, Microsoft.Data.ProviderBase.DbConnectionInternal ByRef) [/_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/ProviderBase/DbConnectionFactory.cs @ 121]
00007F5EC7F2AB70 00007f65667dea2b Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(System.Data.Common.DbConnection, Microsoft.Data.ProviderBase.DbConnectionFactory, System.Threading.Tasks.TaskCompletionSource`1<Microsoft.Data.ProviderBase.DbConnectionInternal>, Microsoft.Data.Common.DbConnectionOptions) [/_/src/Microsoft.Data.SqlClient/netcore/src/Common/src/Microsoft/Data/ProviderBase/DbConnectionInternal.cs @ 347]
00007F5EC7F2ABC0 00007f65667de80c Microsoft.Data.SqlClient.SqlConnection.TryOpen(System.Threading.Tasks.TaskCompletionSource`1<Microsoft.Data.ProviderBase.DbConnectionInternal>, Microsoft.Data.SqlClient.SqlConnectionOverrides) [/_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlConnection.cs @ 1721]
00007F5EC7F2AC00 00007f65667ddbe7 Microsoft.Data.SqlClient.SqlConnection.Open(Microsoft.Data.SqlClient.SqlConnectionOverrides) [/_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlConnection.cs @ 1211]

Any idea if this might already be known? What next step should we do to investigate?

[svick]

As the issue template says, issues shouldn't be created in this repository. Because of that, you should close the issue here and reopen it on the correct repo. For this issue, I think that would be dotnet/SqlClient.

[quanmaiepi]

OK thanks