[HADOOP-15471] Hdfs recursive listing operation is very slow

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.7.1
• Fix Version/s: 2.7.1
• Component/s: fs

Environment

HCFS file system where HDP 2.6.1 is connected to ECS (Object Store).

• Target Version/s: 2.7.6
• Assignee: Ajay Sachdev
• Reporter: Ajay Sachdev
• Created: 04/Apr/18 20:31
• Updated: 08/Jun/18 23:25

Description

The hdfs dfs -ls -R command is sequential in nature and is very slow for a HCFS system. We have seen around 6 mins for 40K directory/files structure.

The proposal is to use multithreading approach to speed up recursive list, du and count operations.

We have tried a ForkJoinPool implementation to improve performance for recursive listing operation.

https://github.com/jasoncwik/hadoop-release/tree/parallel-fs-cli

commit id : 

82387c8cd76c2e2761bd7f651122f83d45ae8876

Another implementation is to use Java Executor Service to improve performance to run listing operation in multiple threads in parallel. This has significantly reduced the time to 40 secs from 6 mins.