Status

Current state: Under DiscussionMerged

Discussion thread: here

JIRA: TBD 

Released: Unreleased

Audience: Cassandra Developers
User Impact: None
Target Release: 4.0.xQ3 2021

Motivation

Like all distributed systems, proving correctness in Cassandra is challenging. We have made great strides in testing with in-jvm dtests, harry and other approaches, however these all require either fairly invasive and deliberate perturbations to the normal ordering of events in the system in order to elicit specific conditions, regressions etc, or they must be made immune to changes in the ordering of events in order for the test to run successfully.

Ideally boundary and unexpected conditions and event orderings could be elicited automatically, without any manual intervention - either for cluster level tests, or those at the component or class level. Tests written only to assert internal consistency of state could then explore far more system behaviours for the same level of investment.

This work dovetails well with Harry, which automates the exploration and validation of different data patterns and workloads. We hope to eventually combine the two approaches.

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