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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4338) Experiment with direct buffer in SequentialWriter
Date Wed, 27 Jun 2012 01:01:58 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4338?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401848#comment-13401848
] 

Jonathan Ellis commented on CASSANDRA-4338:
-------------------------------------------

I'd vote for:

- test with LCS, with/without compression (maybe even reduce sstable size to 1MB to really
stress sstable creation)
- enable gc logging, count promotion failures so we have quantitative data (if we see zero
both ways, we may need a more complex test)
- if instead we see nonzero promotion failures both ways, at about the same rate, we might
need to look at using our "cleaner" hack to free the direct buffers, or use a buffer based
on FreeableMemory, to avoid the phantomreference crap that DirectBuffer normally inflicts
on GC
                
> Experiment with direct buffer in SequentialWriter
> -------------------------------------------------
>
>                 Key: CASSANDRA-4338
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4338
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Yuki Morishita
>            Priority: Minor
>             Fix For: 1.2
>
>         Attachments: gc-4338-patched.png, gc-trunk.png
>
>
> Using a direct buffer instead of a heap-based byte[] should let us avoid a copy into
native memory when we flush the buffer.

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