Zhihua Deng created MAPREDUCE-7241:
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Summary: FileInputFormat listStatus causes oom when there are lots
of files
Key: MAPREDUCE-7241
URL: https://issues.apache.org/jira/browse/MAPREDUCE-7241
Project: Hadoop Map/Reduce
Issue Type: Improvement
Components: job submission
Affects Versions: 2.6.1
Reporter: Zhihua Deng
Attachments: filestatus.png
This case sometimes sees in hive when user issues queries over all partitions
by mistakes. The file status cached when listing status could accumulate to
over 3g. After digging into the dumped memory, the LocatedBlock occupies
about 50%(sometimes over 60%) memory that retained by LocatedFileStatus, as
shows in the filestatus.png attached.
Now we only extract the block locations info from LocatedFileStatus, the
datanode infos(types) or block token are not taken into account. So there is no
need to cache LocatedBlock, as do like this:
```java
BlockLocation[] blockLocations = dedup(stat.getBlockLocations());
LocatedFileStatus shrink = new LocatedFileStatus(stat, blockLocations);
private static BlockLocation[] dedup(BlockLocation[] blockLocations) {
BlockLocation[] copyLocs = new BlockLocation[blockLocations.length];
int i = 0;
for (BlockLocation location : blockLocations) {
copyLocs[i++] = new BlockLocation(location);
}
return copyLocs;
}
```
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