I have an ASP.NET Core application using a SignalR hub. When running via a console application (development mode), no keep-alive requests are sent by the server to the client. Consequently, the connection is re-established every 30 seconds or so.
However, when running the same application via Service Fabric, keep-alive requests are sent and everything works as expected.
Here are the server logs when running under the console app:
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[1]
New connection T2NKQg0jyrm7QAPz4p0ZWA created.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[4]
Establishing new connection.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[5]
OnConnectedAsync started.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[1]
Socket opened using Sub-Protocol: '(null)'.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[9]
Message received. Type: Text, size: 32, EndOfMessage: True.
dbug: Microsoft.AspNetCore.SignalR.Internal.DefaultHubProtocolResolver[2]
Found protocol implementation for requested protocol: json.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionContext[1]
Completed connection handshake. Using HubProtocol 'json'.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[11]
Sending payload: 3 bytes.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[9]
Message received. Type: Text, size: 11, EndOfMessage: True.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[9]
Message received. Type: Text, size: 11, EndOfMessage: True.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[4]
Waiting for the application to finish sending data.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[2]
Socket closed.
trce: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionContext[1]
Disposing connection T2NKQg0jyrm7QAPz4p0ZWA.
trce: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionContext[2]
Waiting for application to complete.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[6]
OnConnectedAsync ending.
trce: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionContext[3]
Application complete.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[2]
Removing connection T2NKQg0jyrm7QAPz4p0ZWA from the list of connections.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[1]
New connection JW_1AnoGvhvNJ6MdWGb5RA created.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[4]
Establishing new connection.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[5]
OnConnectedAsync started.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[1]
Socket opened using Sub-Protocol: '(null)'.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[9]
Message received. Type: Text, size: 32, EndOfMessage: True.
dbug: Microsoft.AspNetCore.SignalR.Internal.DefaultHubProtocolResolver[2]
Found protocol implementation for requested protocol: json.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionContext[1]
Completed connection handshake. Using HubProtocol 'json'.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[11]
Sending payload: 3 bytes.
trce: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[9]
Message received. Type: Text, size: 11, EndOfMessage: True.
And the client logs:
Microsoft.AspNetCore.Http.Connections.Client.HttpConnection: Debug: Transport 'WebSockets' started.
Microsoft.AspNetCore.Http.Connections.Client.HttpConnection: Information: HttpConnection Started.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Information: Using HubProtocol 'json v1'.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Sending Hub Handshake.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Received message from application. Payload size: 32.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Message received. Type: Text, size: 3, EndOfMessage: True.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Handshake with server complete.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Receive loop starting.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Sending PingMessage message.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Received message from application. Payload size: 11.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Sending PingMessage message completed.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Information: HubConnection started.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: The HubConnection is attempting to transition from the Connecting state to the Connected state.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: Releasing Connection Lock in StartAsyncInner (/_/src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs:280).
The thread 0x8184 has exited with code 0 (0x0).
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: Acquired the Connection Lock in order to ping the server.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Sending PingMessage message.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Sending PingMessage message completed.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: Releasing Connection Lock in RunTimerActions (/_/src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs:1881).
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Received message from application. Payload size: 11.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: Waiting on Connection Lock in HandleConnectionClose (/_/src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs:1279).
Microsoft.AspNetCore.Http.Connections.Client.HttpConnection: Debug: Disposing HttpConnection.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Information: Transport is stopping.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Send loop stopped.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Transport stopped.
Microsoft.AspNetCore.Http.Connections.Client.HttpConnection: Information: HttpConnection Disposed.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Debug: Canceling all outstanding invocations.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Receive loop canceled.
Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport: Debug: Receive loop stopped.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Trace: The HubConnection is attempting to transition from the Connected state to the Reconnecting state.
Microsoft.AspNetCore.SignalR.Client.HubConnection: Error: HubConnection reconnecting due to an error.
I won't include them here, but the logs when running under Service Fabric show that the server is correctly sending keep-alives to the client ("Sent a ping message to the client").
It might seem obvious that there is some difference in configuration between my console and Service Fabric hosts, but I've gone through it carefully and cannot see anything that would explain this. In fact, the SignalR integration differed only in that the development host configured detailed errors to be enabled, but even if I remove that the behavior remains the same.
Short of running my own build of ASP.NET Core (something I'm perhaps lazily attempting to avoid only because it was looking far from trivial to build), is there anything I might be missing that would explain this situation?
