RPC call sometimes hangs

[flin-8]

Not sure if this is an issue with IIS, but sometimes an RPC call will hang and never come back when the router is running inside IIS/IIS express.

I've attached a simple website, and a test that repeatedly calls the registered method.
WampSharpTest.zip

Sample log file:
WampClient 2018-01-09 09-49-37Z.log

[darkl]

Tried running your example. I can reproduce the issue when running it against the given IIS express sample.
When using a self-hosted owin host (Microsoft.Owin.SelfHost), I can't reproduce the issue, and the test passes after a long time.

I guess the issue is indeed related to IIS. Unfortunately, I'm don't know much in this area. I would guess that this depends on some IIS configuration, that may or may not be related to WebSockets, but again I don't really know. If anyone can suggest any pointers, it would be appreciated.

Elad

[flin-8]

Thanks for trying that out Elad. I'm losing my sanity over this as our router runs inside IIS in the application...

To give you more info, any subsequent RPC calls on the same channel immediately hangs, so the channel is in a broken state. Do you have any suggestions as to how we could at least make it so we can retry the RPC call on the same channel?

[darkl]

Found the root of the problem: when running on IIS, the tasks returned from the SendAsync method of OwinWebSocketWrapper sometimes never complete. This prevents the ActionBlock from processing new tasks.

I need to think about a solution for this problem. One option is to use the CancellationToken parameter of the SendAsync signature and cancel the operation (and disconnect the channel) after a timeout.

Elad

[darkl]

Reproduced with pure OWIN code, see this issue. You are encouraged to show support in this issue.

[flin-8]

Thanks Elad, appreciate your efforts :)

[flin-8]

FYI, running the router in an ASP.Net Core 2 project also has this problem, and the it hangs much faster

[darkl]

Dear @flin-zap,
this bizarre issue results somehow from the combination of WebSocket4Net and the IIS server. Using WampSharp.WebSockets instead of WampSharp.WebSocket4Net (remove also WampSharp.Default.Client) seems to work as expected:

IWampChannel calleeChannel = _channelFactory.ConnectToRealm(realm)
    .WebSocketTransport(new Uri(_routerUri))
    .JsonSerialization()
    .Build();

IWampChannel callerChannel = _channelFactory.ConnectToRealm(realm)
    .WebSocketTransport(new Uri(_routerUri))
    .JsonSerialization()
    .Build();

Hopefully that will do for now.
Elad

[flin-8]

Thanks @darkl, will give it a go 👍

[darkl]

Resolved in newer Windows versions.