search

Unleash / unleash-client-go

Unleash client SDK for Go
https://docs.getunleash.io
Apache License 2.0
138 stars 55 forks source link

fix: new variant hashing #145

Closed sjaanus closed 12 months ago

sjaanus commented 12 months ago

What

Uses a new seed for ensuring a fair distribution for variants.

Background

After a customer reported that variant distribution seemed skewed we performed some testing and found that since we use the same hash string for both gradual rollout and variant allocation we'd reduced the set of groups we could get to whatever percentage our gradual rollout was set.

Example

Take a gradualRollout of 10%, this will select normalized hashes between 1 and 10, when we then again hash the same string that gave us between 1 and 10, but with modulo 1000 for variants, this will only give us 100 possible groups, instead of the expected 1000.

Fix

Force the normalization to accept a seed, and make sure to use a new seed when normalizing the variant distribution hash.

Worth noting

This will require release 4.0.0, since we are changing how hashing works.

chriswk commented 12 months ago

Client Spec change is here: https://github.com/Unleash/client-specification/pull/68. It was only one failing client spec test for me