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Posted to commits@cayenne.apache.org by "Andrus Adamchik (Jira)" <ji...@apache.org> on 2026/10/12 17:58:00 UTC

[jira] [Updated] (CAY-3049) Cheap ClockMap to replace ConcurrentLinkedHashMap

     [ https://issues.apache.org/jira/browse/CAY-3049?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrus Adamchik updated CAY-3049:
---------------------------------
    Description: 
ConcurrentLinkedHashMap is a nice data structure (its successor is currently maintained  as a part of the Caffeine project). But it is an overkill for our needs and also our older version has some undesired performance costs. Let's replace it with a simple "ClockMap" built on top of ConcurrentHashMap that does some simple sweeping of unused entries. 

This will relax the LRU guarantees (the map size can overshoot sometimes), but we'll gain a noticeable performance boost on select (~20-40%)

  was:
ConcurrentLinkedHashMap is a nice data structure (its successor is currently maintained  as a part of the Caffeine project). But it is an overkill for our needs and also our older version has some undesired performance costs. Let's replace it with a simple "ClockMap" built on top of ConcurrentHashMap that does some simple sweeping of unused entries. 

This will relax the LRU guarantees (the map size can overshoot sometimes), but we'll gain a noticeable performance boost on select (~20%)


> Cheap ClockMap to replace ConcurrentLinkedHashMap
> -------------------------------------------------
>
>                 Key: CAY-3049
>                 URL: https://issues.apache.org/jira/browse/CAY-3049
>             Project: Cayenne
>          Issue Type: Task
>            Reporter: Andrus Adamchik
>            Assignee: Andrus Adamchik
>            Priority: Major
>             Fix For: 5.0-M4
>
>
> ConcurrentLinkedHashMap is a nice data structure (its successor is currently maintained  as a part of the Caffeine project). But it is an overkill for our needs and also our older version has some undesired performance costs. Let's replace it with a simple "ClockMap" built on top of ConcurrentHashMap that does some simple sweeping of unused entries. 
> This will relax the LRU guarantees (the map size can overshoot sometimes), but we'll gain a noticeable performance boost on select (~20-40%)



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