(PECL gearman >= 0.5.0)
GearmanClient::echo — Send data to all job servers to see if they echo it back
Sends some arbitrary data to all job servers to see if they echo it back. The data sent is not used or processed in any other way. Primarily used for testing and debugging.
Some arbitrary serialized data to be echo back
成功した場合に TRUE を、失敗した場合に FALSE を返します。