function print_stack_trace($msg)
{
	error_log("[print_stack_trace][begin]"."====== ".$msg." ======");
	$array =debug_backtrace();
  //print_r($array);//信息很齐全
   unset($array[0]);
   foreach($array as $row)
	{
	   $html ="  ".$row['file'].':'.$row['line'].'  '.$row['function']."  ";
		error_log($html);
	}
	error_log("[print_stack_trace][ end ]"."====== ".$msg." ======");
}