mapreduce任务出错最大尝试次数

mapred-site.xml:
hadoop1.x:
    mapred.max.map.attempts
    mapred.max.reduce.attempts
hadoop2.x:
    <property>
      <name>mapreduce.reduce.maxattempts</name>
      <value>4</value>
      <description>Expert: The maximum number of attempts per reduce task.
      In other words, framework will try to execute a reduce task these many number
      of times before giving up on it.
      </description>
    </property>
    
    <property>
      <name>mapreduce.map.maxattempts</name>
      <value>4</value>
      <description>Expert: The maximum number of attempts per map task.
      In other words, framework will try to execute a map task these many number
      of times before giving up on it.
      </description>
    </property>