Selenium WebDriver exception when multiple processes run in parallel

Question

I have a process, using Selenium Web driver for Firefox, for automatic look up for information on one specific site. Due to the volume of the data being looked up, I am running in parallel several copies of this process. Sometimes they are ok, sometimes I get an exception, which I do not understand the cause for. The Process is written in C#, runs on Windows. Each process creates its own instance of Selenium, FF web driver, I see each process has a separate FireFox process. No multi-treading (inside one process). I do not understand what exactly is the issue. Could not find any documentation that could tell me more. If anyone has an idea, I'd appreciate any info/suggestions

The exception is:

"OpenQA.Selenium.WebDriverException: Unexpected error. System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted 127.0.0.1:7056"

I can not see what can be trying to make more than one "usage" of the socket address in one given process. And from the logs I see that the different processes use different ports ( the "7056" above is a different number in each process).

Thank you in advace

Answer 1

I recently ran into this and found a pretty interesting article about fine tuning your network settings.

https://blogs.msdn.microsoft.com/dgorti/2005/09/18/only-one-usage-of-each-socket-address-protocolnetwork-addressport-is-normally-permitted/

so pretty much if you run a high degree of parallelism in your tests with not enough ports open and a high timeout you will run out of sockets and this will happen. either increase the ports, reduce the wait time and check what can be leaving your instances hanging.