Lightstreamer going into polling mode randomly

GoatHunter

Hi, we're using Lightstreamer moderato, what can cause it to go to polling mode and send a request every second one time and the other time work in streaming mode without a problem?

Thanks.

Alessandro Alinone

There are several heuristic mechanisms in Lightstreamer governing the automatic choice between streaming and polling modes. Did you observe the two different behaviors under the same exact conditions (that is, same machine, same browser, same proxy, same firewall, etc.)? If this is the case, then an explanation could be found in the adaptive mechanism of the Lightstreamer client library. If the client CPU is saturated and cannot process the updates fast enough, it will switch to long polling mode to find the right pace. Did you observe any CPU peak during the state transition?

GoatHunter

I think it started due to heavy traffic on the client's side, since we're settings multiple ajax request asynchrnously every 2-3 seconds or so and using lightstreamer in the same page.

We've enabled keep alive via our apache server so it will persist request, meanwhile performance seems better I guess, but one more thing is troubling me, via firefox and ie we're getting 'Transfering data from ls.server.com' for a long time while, sometimes it goes away and sometimes persists, what can be the cause of that?

Thanks again.

Alessandro Alinone

When in streaming mode, Firefox usually writes "Transferring data" to the status bar, because a download is actually in place (there could be unpredictable cases where Firefox doesn't write such message, but the usual case is to write it). For the same reason, IE writes a similar message, this time mentioning the URL from which it is downloading. In IE7 and IE8 it is not possible to write custom messages to the status bar, so we overloaded the URL syntax to give it some semantics (something like "streaming_in_progress", which can be customized). See this post for more info on this.

A good practice is to notify the user of the current Lightstreamer state through a widget in the application. It could just be a message string or something more sophosticated (for example, see the new status widget to the left-top part of the screen that we use in our demos).