在 Hadoop 中更改文件拆分大小

问题描述

我在 HDFS 目录中有一堆小文件.虽然文件的体积相对较小，但每个文件的处理时间量很大.也就是说，一个 64mb 文件，它是 TextInputFormat 的默认分割大小，甚至需要几个小时来处理.

I have a bunch of small files in an HDFS directory. Although the volume of the files is relatively small, the amount of processing time per file is huge. That is, a 64mb file, which is the default split size for TextInputFormat, would take even several hours to be processed.

我需要做的是减小分割大小，这样我就可以利用更多节点来完成一项工作.

What I need to do, is to reduce the split size, so that I can utilize even more nodes for a job.

所以问题是，如何以 10kb 来分割文件?我是否需要为此实现自己的 InputFormat 和 RecordReader ，或者是否需要设置任何参数?谢谢.

So the question is, how is it possible to split the files by let's say 10kb? Do I need to implement my own InputFormat and RecordReader for this, or is there any parameter to set? Thanks.

推荐答案

mapred.max.split.size这个参数可以根据job单独设置寻找.不要更改 dfs.block.size，因为这对于 HDFS 来说是全局性的，可能会导致问题.

The parameter mapred.max.split.size which can be set per job individually is what you looking for. Don't change dfs.block.size because this is global for HDFS and can lead to problems.

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