For Gearman PHP 1.1.1
sendData() only works for addTask.
It does not work with doNormal, doBackground or addTaskBackground submission types
(PECL gearman >= 0.6.0)
GearmanJob::sendData — Send data for a running job
$data): boolSends data to the job server (and any listening clients) for this job.
dataArbitrary serialized data.
成功时返回 true， 或者在失败时返回 false。