elastic/elasticsearch

Record shard movements over time

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#60,747 opened on Aug 5, 2020

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 (7 comments) (3 reactions) (1 assignee)Java (25,882 forks)batch import
:Distributed/Allocation>enhancementTeam:Distributedhelp wanted

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Description

Sometimes it is useful to know how shards have moved around the cluster on the way to their current locations. Today there is no simple way to obtain this information, even with DEBUG-level logging. We (the @elastic/es-distributed team) discussed this today and we propose introducing a new logger for shard movements in order to expose this information in the logs. This need only look at the cluster state and therefore runs only on the elected master, and should log shard-by-shard changes to the routing table.

I'm marking this as help wanted to invite external contributions since this isn't a priority for us right now, but note that it may not be a straightforward task to implement this correctly and efficiently.

Contributor guide

Research direction
Study the Elasticsearch cluster state and routing table updates on the elected master node; implement a dedicated logger that logs shard by shard changes.
Tech stack
java
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaElasticsearch
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40