hadoop job推测执行
//SPECULATIVE_GAP =0.2(averageProgress - progress >= SPECULATIVE_GAP ) && (currentTime - startTime >= SPECULATIVE_LAG?P.s. 看源码的时候看到调度map task的策略，故记下。JobInProgress添加新的maptask的调度策略// When scheduling a map task://? 0) Schedule a failed task without considering locality//? 1) Schedule non-running tasks//? 2) Schedule speculative tasks//? 3) Schedule tasks with no location informationmap task调度策略：1、失败的task，不考虑地点2、没跑过的task3、推测执行的task4、nonLocalRunningMaps中的task??
?
