[jira] [Commented] (CASSANDRA-8231) Wrong size of cached prepared statements

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14194840#comment-14194840 ] 

Jonathan Ellis commented on CASSANDRA-8231:
-------------------------------------------

JAMM provides something similar with ObjectSizes.

> Wrong size of cached prepared statements
> ----------------------------------------
>
>                 Key: CASSANDRA-8231
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8231
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Jaroslav Kamenik
>            Assignee: Benjamin Lerer
>         Attachments: 8231-notes.txt, Unsafes.java
>
>
> Cassandra counts memory footprint of prepared statements for caching purposes. It seems, that there is problem with some statements, ie SelectStatement. Even simple selects is counted as 100KB object, updates, deletes etc have few hundreds or thousands bytes. Result is that cache - QueryProcessor.preparedStatements  - holds just fraction of statements..
> I dig a little into the code, and it seems that problem is in jamm in class MemoryMeter. It seems that if instance contains reference to class, it counts size of whole class too. SelectStatement references EnumSet through ResultSet.Metadata and EnumSet holds reference to Enum class...



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