I am working on a product that recently migrated from IIS to Apache 2.2. The product has an ISAPI extension that needs to support thousands of concurrent clients. Since IIS supports asynchronous I/O, the ISAPI extension component has been designed to leverage the benefits of asynchronous I/O. However, Apache doesn't support asynchronous I/O, and we are considering a custom implementation over the latest stable release. Before doing that, I wanted to check if someone is aware of asynchronous I/O support being added to Apache, or if someone has already done a custom implementation that they would be willing to share. Nick Kew claims in his book - The Apache Modules - that Apache 2.4 is going to support asynchronous I/O and that the code is already there in trunk. I got the latest code from trunk, but couldn't find anything to suggest that asynchronous I/O has been added. Please let me know if you believe that the code is there in trunk and that I overlooked it. We need to have this done as early as possible, as the product ships in June-July 2010 time-frame.