[HDFS-6982] nntop: top­-like tool for name node users

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.7.0
• Assignee: Maysam Yabandeh
• Reporter: Maysam Yabandeh
• Created: 02/Sep/14 20:53
• Updated: 30/May/19 18:42
• Resolved: 18/Nov/14 01:35

Description

In this jira we motivate the need for nntop, a tool that, similarly to what top does in Linux, gives the list of top users of the HDFS name node and gives insight about which users are sending majority of each traffic type to the name node. This information turns out to be the most critical when the name node is under pressure and the HDFS admin needs to know which user is hammering the name node and with what kind of requests. Here we present the design of nntop which has been in production at Twitter in the past 10 months. nntop proved to have low cpu overhead (< 2% in a cluster of 4K nodes), low memory footprint (less than a few MB), and quite efficient for the write path (only two hash lookup for updating a metric).

Issue Links

• is duplicated by: HDFS-9692 Report Top Namenode rpc consumers through JMX
• is related to: HADOOP-11301 [optionally] update jmx cache to drop old metrics
• is related to: HDFS-7426 Change nntop JMX format to be a JSON blob
• relates to: HDFS-6185 HDFS operational and debuggability improvements
• relates to: HDFS-14524 NNTop total counts does not add up as expected
• relates to: HDFS-7465 Html view for nntop: top users of name node
• relates to: HDFS-10984 Expose nntop output as metrics