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组合器处理映射器的输出记录。如果将映射器输出记录馈送到组合器，那么为什么我的组合器输入记录多于映射器输出记录？

我额外获得了这 80 条记录。我不知道它们来自哪里以及它们的价值是什么。

Mapreduce 的纱线转储：

 Map-Reduce Framework
            Map input records=80000000
            Map output records=80000000
            Map output bytes=2560000000
            Map output materialized bytes=80
            Input split bytes=220
            Combine input records=80000083
            Combine output records=85
            Reduce input groups=1
            Reduce shuffle bytes=80
            Reduce input records=2
            Reduce output records=3
            Spilled Records=87
            Shuffled Maps =2
            Failed Shuffles=0
            Merged Map outputs=2
            GC time elapsed (ms)=4124
            CPU time spent (ms)=90530
            Physical memory (bytes) snapshot=573521920
            Virtual memory (bytes) snapshot=2509766656
            Total committed heap usage (bytes)=411041792
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