[HDFS-8681] BlockScanner is incorrectly disabled by default

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.7.0
• Fix Version/s: 2.8.0, 2.7.1, 3.0.0-alpha1
• Component/s: datanode
• Hadoop Flags: Reviewed
• Assignee: Arpit Agarwal
• Reporter: Andrew Wang
• Created: 26/Jun/15 23:02
• Updated: 05/Jan/17 22:42
• Resolved: 28/Jun/15 21:54

Description

This code is used to check whether the block scanner is enabled:

  public boolean isEnabled() {
    return (conf.scanPeriodMs) > 0 && (conf.targetBytesPerSec > 0);
  }

Unfortunately, when this was introduced, we did not change the default scan period's value of 0, which means by default the BlockScanner is disabled.

Issue Links

• is broken by: HDFS-7430 Rewrite the BlockScanner to use O(1) memory and use multiple threads
• is related to: HDFS-8691 Cleanup BlockScanner initialization and add test for configuration contract