[AMBARI-21593] RU: AMS stopped after RU [AMS distributed mode]

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 2.5.2
• Fix Version/s: 2.5.2
• Component/s: ambari-metrics
• Assignee: Aravindan Vijayan
• Reporter: Aravindan Vijayan
• Created: 27/Jul/17 22:52
• Updated: 31/Jul/17 22:31
• Resolved: 31/Jul/17 21:31

Description

PROBLEM
When 2 metric collectors are started up simultaneously, both of them fail to start.

BUG
There exists a race condition in the Metric Collector HA controller initialization which was introduced through AMBARI-20179. When a helix controller instance finds that the /ambari-metrics-collector znode exists but a child node does not exists, it deletes the entire znode and recreates. If another controller instance also initializes simultaneously, a race condition can occur wherein each instance will end up cancelling the effort of the other.

FIX
Do not delete and recreate the znode. Wait and retry for a few seconds to check if /ambari-metrics-collector was fully initailized.

Issue Links

• links to: Review Board