hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Charles Lamb (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7435) PB encoding of block reports is very inefficient
Date Thu, 26 Feb 2015 23:16:05 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339390#comment-14339390
] 

Charles Lamb commented on HDFS-7435:
------------------------------------

bq. I mildly disagree will overly verbose message for UnsupportedOperationExceptions since
the JDK rarely uses message and the class & method is in the stack trace.

Yeah, I figured there was a reason for not having a message in the UOE, so it won't cause
me any heartburn if you don't put them in.

bq. I think the whole fragmented over-the-write buffer implementation is over engineered.

Oh, I kind of liked it.

I'll try to take a look at the new patch soon. Thanks for the reply.


> PB encoding of block reports is very inefficient
> ------------------------------------------------
>
>                 Key: HDFS-7435
>                 URL: https://issues.apache.org/jira/browse/HDFS-7435
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: datanode, namenode
>    Affects Versions: 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>         Attachments: HDFS-7435.000.patch, HDFS-7435.001.patch, HDFS-7435.002.patch, HDFS-7435.patch,
HDFS-7435.patch, HDFS-7435.patch
>
>
> Block reports are encoded as a PB repeating long.  Repeating fields use an {{ArrayList}}
with default capacity of 10.  A block report containing tens or hundreds of thousand of longs
(3 for each replica) is extremely expensive since the {{ArrayList}} must realloc many times.
 Also, decoding repeating fields will box the primitive longs which must then be unboxed.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message