[HDFS-8989] Allow rate-limiting the DirectoryScanner via time-slicing

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.0.6-alpha
• Component/s: datanode
• Target Version/s: 2.8.0
• Assignee: Daniel Templeton
• Reporter: Colin McCabe
• Created: 28/Aug/15 20:27
• Updated: 03/Sep/15 02:10
• Resolved: 02/Sep/15 16:52

Description

When the inodes and directory entries for HDFS block and meta files are not in the cache, the DirectoryScanner can create enormous disk load via generating many seeks. This can effectively make the disks unusable for other purposes. We should allow rate-limiting the DirectoryScanner via time-slicing, so that it only runs every 100 ms out of 1 s (or whatever other percentage we configure.)

Issue Links

• duplicates: HDFS-8873 Allow the directoryScanner to be rate-limited