配置选项 默认值 mapreduce.map.java.opts -Xmx512m mapreduce.reduce.java.opts -Xmx768m mapreduce.map.memory.mb 768 mapreduce.reduce.memory.mb 1024 yarn.app.mapreduce.am.resource.mb 1024 yarn.scheduler.minimum-allocation-mb 256 yarn.scheduler.maximum-allocation-mb 2048 yarn.nodemanager.resource.memory-mb 2048