(PECL gearman >= 0.5.0)
GearmanClient::doLow — Run a single low priority task
$function_name
   , string $workload
   [, string $unique
  ] )Runs a single low priority task and returns a string representation of the result. It is up to the GearmanClient and GearmanWorker to agree on the format of the result. Normal and high priority tasks will get precedence over low priority tasks in the job queue.
function_name
     由程序自动执行的已注册函数。
workload
     被处理的序列化数据
unique
     用于标识特定任务的唯一 性ID。
A string representing the results of running a task.