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Arnon Rotem-Gal-Oz

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Windows Trick-or-treat Foundation

October 30, 2009

Yes, this is another WCF rant…

We were getting ready to launch an open-for-all version of our service, we were also adding more cores to the system, to make sure our computation engine will be able to handle higher request loads (We’re basically implementing the Gridable Service pattern -  if it is interesting, I can expand on that in another post). We tried a few load tests, which on first look, seemed OK. However we then noticed that we get WCF timeouts on some of the calls.

WCF timeouts!? what gives? we already took care of all the annoying throttling defaults. After busting my head (and Google) for a few hours, I found that apparently, when using http bindings in WCF you only get 2 outgoing channels for each server (IP) you are connecting to. yep WCF thinks your services are novice users using a  browser. So if you have a service that tries to access a remote server with more than two requests simultaneously (say, under load…) you may find, like us, that you’d get occasional timeouts.

Yes, there’s also a solution, which also took time to find – it is called ConnectionManagment element in the network configuration (I am yet to find a programmable way to do this). So now the services app.config (see below) sets the value to 16 instead of 2 and everything is well again, at least until the next default hits us..

<span style="color: blue"><</span><span style="color: #a31515">system.net</span><span style="color: blue">><br />   <</span><span style="color: #a31515">connectionManagement</span><span style="color: blue">><br />     <</span><span style="color: #a31515">add </span><span style="color: red">address </span><span style="color: blue">= </span>"<span style="color: blue">*</span>" <span style="color: red">maxconnection </span><span style="color: blue">= </span>"<span style="color: blue">16</span>" <span style="color: blue">/><br />   </</span><span style="color: #a31515">connectionManagement</span><span style="color: blue">><br /> </</span><span style="color: #a31515">system.net</span><span style="color: blue">></span>

 

From trying to work with WCF in the last few years, it seems its abstractions are very leaky.They are almost leaky  to the point  of rendering it useless as a “unified” framework. So, in the spirit of the times, and as the title suggest – maybe they should just rename WCF to Windows Trick-or-treat Foundation – Alas, we are getting more and more of the “trick’ part rather that the expected  “treat”, but at least the acronym fits well.

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