In two previous posts, the AlternateInterior blog looked at working with threading in PHP. They continue along this path with this new post today - benchmarking some of their threading techniques.
All threads can now both hear and report on conditions. A problem with the original send/receive mechanism made threads hang the controlling thread while long operations were occurring.
After updating some of their HVAC class to make it a little easier to understand/use, they ran some benchmarks on running processes two different ways - multithreaded and sequential.
The package is available for download if you'd like to work with it/run the tests yourself.