Strange TimeoutException in WCF

Question

I have a web application that is talking to a WCF service hosted within a Windows Service. Every once in a while I will start seeing EventLog errors that stating that the request to the WCF service timed out after 1 minute. I understand that error (although why it would take that long to respond is a mystery). The error that really confuses me is this one:

Open timed out after 00:00:00 while establishing a transport session to net.pipe://localhost/service

I am calling Close() on all my client proxies, so I am 99% sure there are no left open connections. So my only thought is that I may be running out of connections, as the MaxConnections for the WCF service is set to 3000, and each web applications is set to use 1000. My gut reaction is that all the connections are being used up, and they are timing out while being queued. However, I have no way to prove it (that I am aware of).

These calls should take, at the absolute max, a second or two (avg is a few hundred miliseconds).

1. Can anyone give me a pointer on what the error posted above could be caused by?

2. Is there a way for a WCF service to service an unlimited amount of connections?

   2a. If not, what are the ramifications of setting the max connections to something like 10,000?

Answer 1

1. try to turn on WCF logging and see if you can find something more helpful there.
2. No there is not. 2a. You're probably going to get exceptions as you'll use up all resources (phisical connections, handler threads, memory). I'm also pretty sure there's a limit in the OS itself and that its greatly lower than 10000