keep() public method

keep sub process count
public keep ( boolean $block = false, integer $interval = 100 )
$block boolean block the master process to keep the sub process count all the time
$interval integer check time interval
 /**
  * keep the sub processes count
  *
  * @param bool $block
  */
 public function keep($block = false)
 {
     $this->pool->keep($block);
 }