When you are facebook's scale, there is no off-the-shelf solution. Whatever they choose to do, it's most likely going to be their own effort. There is nothing t

When you are facebook's scale, there is no off-the-shelf solution. Whatever they choose to do, it's most likely going to be their own effort. There is nothing that bad about the PHP language and the fact that all their developers know it, it makes sense that they keep the language, just change what runs it.