.NET Client throwing "Session not found" error

vpurohit

When sending multiple notifications, our .NET client session not found error. Sometimes we get this error right after receiving 1st notification and sometimes after receiving 10 notifications.

Here is what we see in client logs -

Lightstreamer.DotNet.Client.PushServerException: Session not found
at Lightstreamer.DotNet.Client.PushServerTranslator.CheckAnswer(LSStreamReader answer)
at Lightstreamer.DotNet.Client.PushServerProxy.ResyncSession()
at Lightstreamer.DotNet.Client.ServerManager.Rebind(ActivityController activityController)

Server logs shows -

08-Jul-16 17:56:32,819|INFO |LightstreamerLogger.requests |SERVER POOLED THREAD 10 |Sync error: Can't find session S5d3e6790e70d1262T5446234 on "Lightstreamer HTTP Server" from 10.34.47.4:22524 []

We are using the latest version of .NET Client SDK

Also, we changed ConnectionInfo.ContentLength to 0, so server can set the content length but didn't make any difference.

Any idea on what could go wrong?

Giuseppe Corti

Hi vpurohit,

It seems that this is a case in which the client fails to complete successfully the operation of session rebind (at least within a certain period of time).
However it seems strange to me that this happens also after a single notification received from the server. It was very large notification that exhaust the content length by itself, or it is a polling mode session that lives for a long time.

Anyway, please could you isolate one or two cases of this type and send (to support@lightstreamer.com) the complete log of the client and a snippet of the server log that includes the entire life of the blamed session?

In cases like this it is always better to keep the content length value as large as possible, so I would keep the default value or even bigger. Instead, the value chosen by the server is quite small in the factory configuration.
Finally, please could you confirm the exact version of the client lib in use? I am asking this because in the recent version 2.1.1 build 1013 have been introduced bug fixes just concerning the rebind operation.

Regards,
Giuseppe

vpurohit

Giuseppe Corti Hi vpurohit,

It seems that this is a case in which the client fails to complete successfully the operation of session rebind (at least within a certain period of time).
However it seems strange to me that this happens also after a single notification received from the server. It was very large notification that exhaust the content length by itself, or it is a polling mode session that lives for a long time.

Anyway, please could you isolate one or two cases of this type and send (to support@lightstreamer.com) the complete log of the client and a snippet of the server log that includes the entire life of the blamed session?

In cases like this it is always better to keep the content length value as large as possible, so I would keep the default value or even bigger. Instead, the value chosen by the server is quite small in the factory configuration.
Finally, please could you confirm the exact version of the client lib in use? I am asking this because in the recent version 2.1.1 build 1013 have been introduced bug fixes just concerning the rebind operation.

Regards,
Giuseppe

Thanks for quick update. We'll re-run the test and provide the logs soon.
Btw - it is 2.1.1 build 1013 for us. Should we downgrade to the previous build in this case?

Giuseppe Corti

Hi vpurohit,

I confirm that you should use version 2.1.1 build 1013.

Regards,
Giuseppe

gchermennov

I still see this exact error when using version 2.1.6080.19963 of the client SDK. Can you advise me on how to turn on client logging?

Giuseppe Corti

Hi gchermennov,

You can leverage the the Log4NET library (that must be included in the project - log4net.dll) and a proper configuration.
You can take this example (https://github.com/Lightstreamer/Lightstreamer-example-Quickstart-client-dotnet) as a reference and in particular:

- the configuration file of the app https://github.com/Lightstreamer/Lightstreamer-example-Quickstart-client-dotnet/blob/master/src/TestClient.exe.config
where you can raise the log level for the categories that interest you.
- The code that adds a logger provider to the Lightstreamer client library: https://github.com/Lightstreamer/Lightstreamer-example-Quickstart-client-dotnet/blob/master/src/TestClient.cs#L74

Regards,
Giuseppe

gchermennov

I can't find Log4NetLoggerProviderWrapper class in client dll

gchermennov

Found the class

gchermennov

Ok, here's what I've found after enabling client logs:

2017-01-20 23:55:44,421 [Lightstreamer listening thread] ERROR com.lightstreamer.ls_client.session - Error while listening for data in session xyz
2017-01-20 23:55:44,428 [Lightstreamer listening thread] INFO com.lightstreamer.ls_client.session - Terminating session xyz

These were logs generated by the Lightstreamer client library. Here's what my code says at the same time:

[Stream-sense queue] ERROR ProjectName.Listeners.StreamerListener - lightstreamer::communication::failure - communication failed Lightstreamer.DotNet.Client.PushConnException: Unable to read data from the transport connection: The connection was closed. ---> System.IO.IOException: Unable to read data from the transport connection: The connection was closed.

How can I investigate this further?

Giuseppe Corti

Hi gchermennov,

The error messages reported indicate a disconnection of the communication with the server detected by the client library.
The most common cause for this type of error is a network problem, maybe a temporary network failure, could this be your case?
Otherwise you should make sure that is not the server, for some reason, deliberately terminating the connection, but in this case you need to analyze the Lightstreamer server logs.

Regards,
Giuseppe

gchermennov

Lightstreamer server is not under my control - I just use it to receive data updates.
Network problem can indeed be my case, I'll add code for reconnecting and continue to monitor the situation. Thanks