分区排序溢写为小文件
hadoop1 reduce1spack1 reduce1
80%以后则溢写
spack1 reduce2word1 reduce2word1 reduce2
Map task1
word1 reduce2
调用Reduce方法
分为多个小文件
spack1 reduce1spacke1 reduce2word1 reduce2
合并为一个大文件
hadoop1 reduce1hello1 reduce1spack1 reduce1word1 reduce2
spack{1，1}word{1，1 }
分组
spack1 reduce1word1 reduce2
Reduce端shuffle开始
spack1 reduce2word1 reduce2
Reduce task1
hadoop {1，1}hello{1，1} spack{1，1}
hadoop1 reduce1hadoop1 reduce1hello1 reduce1hello1 reduce1spack1 reduce1spack1 reduce1
hadoop1 reduce1hello1 reduce1spack1 reduce1
spack1hadoop1hello1word1
进入Map端shuffle
hadoop1 reduce1hello1 reduce1spack1 reduce1spack1 reduce2word1 reduce2
spack1hadoop1hello1word1spack1
每个reduce去每个map里拿到自己分区的数据
合并排序
Map端shuffle结束
环形缓冲区
