Job Counters
    Launched map tasks=3
    Launched reduce tasks=45
    Data-local map tasks=1
    Rack-local map tasks=2
    Total time spent by all maps in occupied slots (ms)=29338
    Total time spent by all reduces in occupied slots (ms)=200225
    Total time spent by all map tasks (ms)=29338
    Total time spent by all reduce tasks (ms)=200225
    Total vcore-seconds taken by all map tasks=29338
    Total vcore-seconds taken by all reduce tasks=200225
    Total megabyte-seconds taken by all map tasks=30042112
    Total megabyte-seconds taken by all reduce tasks=205030400

“vcore秒”是什么意思，“vcore秒”和“花费的总时间”有什么区别