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https://issues.apache.org/jira/browse/CASSANDRA-18904?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Abe Ratnofsky updated CASSANDRA-18904:
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    Summary: Repair vtable caches consume excessive memory  (was: Repair vtable 
caches )

> Repair vtable caches consume excessive memory
> ---------------------------------------------
>
>                 Key: CASSANDRA-18904
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-18904
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Consistency/Repair, Local/Caching
>            Reporter: Abe Ratnofsky
>            Assignee: Abe Ratnofsky
>            Priority: Normal
>
> Currently, the repair vtables 
> (system_views.{repairs,repair_sessions,repair_jobs,repair_participates,repair_validations})
>  are backed by caches in ActiveRepairService that are bounded by the number 
> of elements in them, controlled by Config.repair_state_size and 
> Config.repair_state_expires.
> The individual cached elements are mutable, and can grow to retain a 
> significant amount of heap as the instance uptime increases and more repairs 
> are run. In a heap dump for a real cluster, I found these caches occupying 
> ~1GB of heap total between ActiveRepairService.repairs and 
> ActiveRepairService.participates. Individual cached elements were reaching 
> 100KB in size, so configuring the caches by number of elements introduces a 
> significant amount of potential variance in the actual heap usage of these 
> caches.
> We should measure these caches by the heap they retain, not by the number of 
> elements. Users should not be expected to check heap dumps to calibrate the 
> number of elements they configure the caches to consume - specifying a memory 
> total is much more user-friendly.



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