Dmitry Konstantinov created CASSANDRA-20804:
-----------------------------------------------
Summary: Optimize DataPlacement lookup by ReplicationParams
Key: CASSANDRA-20804
URL: https://issues.apache.org/jira/browse/CASSANDRA-20804
Project: Apache Cassandra
Issue Type: Improvement
Components: Consistency/Coordination, Transactional Cluster Metadata
Reporter: Dmitry Konstantinov
Assignee: Dmitry Konstantinov
Attachments: image-2025-07-30-18-39-40-063.png
When we execute a plain write to identify replicas we do several lookups from
ClusterMetadata.placements map using ReplicationParams.
Equals and hashcode for ReplicationParams objects are not very cheap, so there
is a noticible overhead for this logic in CPU profile (0.77% of overall CPU
usage for a plain write Cassandra stress test):
!image-2025-07-30-18-39-40-063.png|width=700!
To reduce it the following optimisations can be applied:
# Avoid double lookup in of the same DataPlacement in
forNonLocalStrategyTokenRead and forNonLocalStrategyTokenWrite
# Memorize hashCode value
# Deduplicate ReplicationParams to use the same objects in DataPlacements and
KeyspaceMetadata to use the fast == path in the equals
The last two optimizations are safe because ReplicationParams is immutable.
Note: it is related to TCM logic, so it is trunk only issue.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org
For additional commands, e-mail: commits-h...@cassandra.apache.org
