(PECL eio >= 0.0.1dev)
eio_busy — Artificially increase load. Could be useful in tests, benchmarking
$delay
[, int $pri = EIO_PRI_DEFAULT
[, callable $callback = NULL
[, mixed $data = NULL
]]] ) : resource
eio_busy() artificially increases load taking
delay seconds to execute. May be used for debugging,
or benchmarking.
delayDelay in seconds
pri请求的优先级：EIO_PRI_DEFAULT，EIO_PRI_MIN，EIO_PRI_MAX 或 NULL。如果是
NULL，pri 将设为
EIO_PRI_DEFAULT。
callbackThis callback is called when all the group requests are done.
data
Arbitrary variable passed to callback.
eio_busy() returns request resource on success or FALSE on error.