Eio is a new PECL extension for asynchronous POSIX I/O.
Eio provides interface for the libeio library. It means that each POSIX call runs in a separate thread. It is important to aware that the order of ungrouped requests is not precisely known. However, libeio, as well, as eio, supports complex call creation to accumulate a set of regular eio_* requests in a single group request. This allows to create a group request ex. to open, read and close a file.
Currently Windows platforms are not supported.
Any extension-specific suggestions are welcome :)