[ACCUMULO-3957] Consider moving off getContentSummary in the monitor

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Component/s: monitor
• Assignee: Josh Elser
• Reporter: Josh Elser
• Created: 11/Aug/15 00:52
• Updated: 29/Aug/15 21:51
• Resolved: 29/Aug/15 21:02

Description

Recently heard about an issue where a large Hadoop installation which had Accumulo running was experiencing long pauses in the Namenode. Inspecting NN audit logs, it was found that the user running Accumulo issues a getContentSummary("/") call just before the NN pauses were experienced.

In DefaultServlet.java, we use this call to compute the total HDFS disk usage and present a ratio of space that Accumulo uses relative to the total available space.

It's still unclear why this was causing issues in this case (as this operation should only be acquiring a read-lock in the namenode), it was recommended to me that Accumulo use the JMX metrics for the NN instead of making this call.

Issue Links

• is related to: HDFS-8046 Allow better control of getContentSummary