[AMBARI-18619] Optimize Service Checks to it picks a random host and prefers hosts with 0 active commands

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.5.0
• Component/s: ambari-server
• Assignee: Alejandro Fernandez
• Reporter: Alejandro Fernandez
• Created: 18/Oct/16 00:31
• Updated: 19/Oct/16 18:48
• Resolved: 19/Oct/16 18:07

Description

STR:

• Deploy a 3-node cluster with Ambari 2.4 and HDP 2.5 with clients on every host.
• Run multiple service checks in parallel, but notice that they typically run on the same 1 or 2 hosts.

Currently, Ambari relies on getting the list of candidate hosts from the DB and excludes all hosts that are in maintenance mode. From that list, it picks the first host that is healthy (i.e., heartbeating). This means that the logic does not pick a random host.

Instead, Ambari should always pick a random host and prefer to schedule on hosts that have 0 in-progress commands.

Issue Links

• links to: Review Board patch