How do you guys batch requests in PHP? You don't, right? So this is an intermediate layer basically, and it sends requests every few millisecods and waits to batch things in between?
The systems described here isn't directly involved with any PHP code.
Like all Facebook services, they are communicated with over the Thrift RPC system, and may have PHP (or any other language) clients, and may talk to other services using Thrift (or occasionally other protocols), some of which may use PHP.
If you want to have similar query parallelization magic for PHP+SQL have a look at the standalone SQLTap service written by the guys from DaWanda.com (https://github.com/paulasmuth/sqltap).
