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From "Joel Knighton (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-13533) ColumnIdentifier object size wrong when tables are not flushed
Date Wed, 24 May 2017 20:50:04 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16023663#comment-16023663
] 

Joel Knighton commented on CASSANDRA-13533:
-------------------------------------------

The patch looks good. I merged this forward through 3.11 and trunk - testall and dtests look
good for all branches relative to upstream.

I'm not sure about including the test as written; it passes on 3.11 and trunk even before
the fix because of the default of offheap memtables introduced in [CASSANDRA-9472]. It seems
to me that we might as well reduce this test to just checking that interning a ColumnIdentifier
uses a minimal bytebuffer and add it to {{ColumnIdentifierTest}}.

> ColumnIdentifier object size wrong when tables are not flushed
> --------------------------------------------------------------
>
>                 Key: CASSANDRA-13533
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13533
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Eduard Tudenhoefner
>            Assignee: Eduard Tudenhoefner
>             Fix For: 3.0.14, 3.11.0, 4.0
>
>         Attachments: columnidentifier.png
>
>
> It turns out that the object size of {{ColumnIdentifier}} is wrong when *cassandra.test.flush_local_schema_changes:
false*. This looks like stuff is being wrongly reused when no flush is happening.
> We only noticed this because we were using the prepared stmt cache and noticed that prepared
statements would account for *1-6mb* when *cassandra.test.flush_local_schema_changes: false*.
With *cassandra.test.flush_local_schema_changes: true* (which is the default) those would
be around *5000 bytes*.
> Attached is a test that reproduces the problem and also a fix.
> Also after talking to [~jkni] / [~blerer] we shouldn't probably take {{ColumnDefinition}}
into account when measuring object sizes with {{MemoryMeter}}



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