envoyproxy/envoy

proportional reconnect to new host for random load balanced xDS

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#9,575 opened on Jan 6, 2020

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area/load balancingarea/xdsdesign proposalhelp wanted

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Description

Title: proportional reconnect to new host for random load balanced xDS

Description: When using random load balancing for the xDS cluster, new hosts entering the pool will sit idle until clients reconnect. It'd be a neat feature if each xDS client noticed the new host being added (or going healthy if health checks are used) and did a 1/N "dice roll" to decide whether to reconnect to the new host. That way new hosts would be added into rotation quickly and you'd quickly converge to roughly even load across the pool.

Contributor guide

Research direction
Examine the random load balancing implementation in Envoy's xDS client. Understand the host set update process and implement a probabilistic reconnect mechanism when new hosts are added.
Tech stack
None
Domain
api
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
C++Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35