[CASSANDRA-18669] Concurrency is broken in the block balanced tree for queries

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 5.x
• Component/s: Feature/SAI
• Epic Link: CEP-7 Storage Attached Index (SAI)
• Bug Category: Correctness - Unrecoverable Corruption / Loss
• Severity: Critical
• Complexity: Low Hanging Fruit
• Discovered By: Performance Regression Test
• Platform: All
• Since Version: NA

Source Control Link

https://github.com/apache/cassandra/commit/83419e074d131a68112470fc8761c3edafb5e675

Test and Documentation Plan

The CI for the patch is here: https://app.circleci.com/pipelines/github/mike-tr-adamson/cassandra/193/workflows/3425e4a2-bce0-46ff-b4c0-a501d422a0f4

• Assignee: Mike Adamson
• Reporter: Mike Adamson

Authors

Mike Adamson

Reviewers

Andres de la Peña, Caleb Rackliffe

• Created: 14/Jul/23 11:05
• Updated: 19/Jul/23 20:33
• Resolved: 17/Jul/23 11:09

Description

Performance testing has highlighted that concurrent queries are broken against the block balanced tree because the mutable traversal state was pushed up to the walker that is linked to an SSTableIndex so is shared amongst all queries.

A new traversal state should be created for each query and marked as not threadsafe. We should add a test to show that concurrent queries work against the block balanced tree.

Issue Links

• links to: PR cep-7-sai