MRUnit單元測試Mapper和Reducer類在內(nèi)存上獨立運行, PipelineMapReduceDriver單線程運行.
LocalJobRunner單線程運行, 且僅有一個 Reducer能夠啟動conf.set("mapred.job.tracker", "local"); conf.set("fs.default.name", "file:////"); FileSystem fs = FileSystem.getLocal(conf);
MiniMRCluster, MiniYarnCluster, MiniDFSCluster 多線程
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