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I have a rather simple worflow hosted on AppFabric. I call it through a WCF endpoint using netTcpBinding, and it calls 2 WCF methods, also via netTcpBinding, hosted on the same server also on AppFabric. I can load test both of the WCF methods being called by the workflow simultaneously without any problems. However, when I start Load Testing the workflow, after a few seconds, when I'm around 10 simultaneous users, the WorkFlows locks up completely, and I'm unable to find out why. All clients starts raising Open Connection timeouts.
The problem is not locking on the SQL Server database, because I monitor it, and it's all go. All tables involved are lock free. I think the problem might be on MSTSC, since I start a transaction scope on the workflow, but how could I detect the problem there? The dashboard on dcomcnfg really doesn't help at all.
How can I find out where's the problem? What could be the problem. Any help would be greatly appreciated.

EDIT

About throttling, I have configured by web.config as follows below:

<behaviors>
  <serviceBehaviors>
    <behavior name="">
      <serviceMetadata httpGetEnabled="true" />
      <serviceDebug includeExceptionDetailInFaults="true" />
      <serviceThrottling maxConcurrentCalls="64" maxConcurrentSessions="400" maxConcurrentInstances="464" />
    </behavior>
  </serviceBehaviors>
</behaviors>

And looking at AppFabric's configuration interface, I can confirm these values for the IIS application that hosts the workflow Tks

Pascal
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1 Answers1

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There could be a throttling issue. The default MaxConcurrentSessions is 10, and because you could be reaching this max, you're seeing the effects. Check out this link:

Thelonias
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  • Ryan, tks for the response... theoretically, I have that taken care of with this entry in web.config. I have edited my question to embed it. I'd appreciate ANY other input. Tks so much – Pascal Apr 13 '11 at 19:41
  • I'm not sure what other input I could give regarding your initial questions. Are you able to test past 10 "users" now? If so, it looks like we've found the answer, otherwise, we'll need to figure something else out. – Thelonias Apr 14 '11 at 12:17
  • The configuration was already like that. The MaxConcurrentSessions was default to 10 on WCF 3.5, and on 4, they have some rules that makes de default 100 * processors count. Besides, I don't think if it was a throttle issue, I'd get bad performance, not locking. And the WCF methods the workflow calls are not locked. I was thinking about MTDTC, mas the debug tools for it are kinna awfull. – Pascal Apr 14 '11 at 16:13