After installing the latest mini-update to Java 6 this morning (around 10am GMT, 29th Oct), successive mongo queries through the C# driver use an auto-incremented port number, similar to when opening the mongo shell multiple times through the command line. This caused queries to time out on a machine running an Intel Core 2 Duo T7700 @ 2.40 GHz with 4GB RAM. Two other more powerful machines were able to run our system without timeouts, despite replicating the port increment issue.

This issue was replicated with drivers 1.6.0.4624 and later 1.6.4678, but only after installing the mentioned Java update. Up until last week we had been using driver version 1.3.1.4349, to which we have been forced to roll back, pending a resolution to this issue. Because we have been forced to roll our driver back, some of our code which used Query.In had to be reverted.

The attached screenshot was created by running a service with a timer event which queries our database once every ten seconds.