[SAMZA-2169] Preventing task-shuffle after task mode addition

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2
• Assignee: Unassigned
• Reporter: Rayman
• Created: 19/Apr/19 17:11
• Updated: 11/Jun/19 22:06
• Resolved: 11/Jun/19 22:06

Description

After adding task-mode, the first re-deployment of an existing job will not have any existing task-modes to read from the coordinator stream. Due to this the existing task-container mapping of the job does not get read. 
In this case, the grouper will re-assign the tasks to containers in lexicographic order, whereas the previous task-container mapping may have been different than this (based on how the job changed over time – because on topic addition a grouper tries to be as close to existing task-grouping as possible). 

Due to this regrouping, task-container mapping will shuffle, causing some containers to get new tasks, who's store need seeding from Kafka on deployment. This can increase job re-deployment time for the first re-deploy. 

Note that, after the first re-deploy the behavior becomes stable as before.

Issue Links

• links to: GitHub Pull Request #1004