hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9079) Erasure coding: preallocate multiple generation stamps and serialize updates from data streamers
Date Wed, 18 Jan 2017 23:34:27 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15828977#comment-15828977
] 

Hadoop QA commented on HDFS-9079:
---------------------------------

| (x) *{color:red}-1 overall{color}* |
\\
\\
|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue}  0m  0s{color} | {color:blue}
Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red}  0m  5s{color} | {color:red}
HDFS-9079 does not apply to trunk. Rebase required? Wrong Branch? See https://wiki.apache.org/hadoop/HowToContribute
for help. {color} |
\\
\\
|| Subsystem || Report/Notes ||
| JIRA Issue | HDFS-9079 |
| JIRA Patch URL | https://issues.apache.org/jira/secure/attachment/12775130/HDFS-9079.15.patch
|
| Console output | https://builds.apache.org/job/PreCommit-HDFS-Build/18203/console |
| Powered by | Apache Yetus 0.5.0-SNAPSHOT   http://yetus.apache.org |


This message was automatically generated.



> Erasure coding: preallocate multiple generation stamps and serialize updates from data
streamers
> ------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-9079
>                 URL: https://issues.apache.org/jira/browse/HDFS-9079
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: erasure-coding
>    Affects Versions: HDFS-7285
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
>         Attachments: HDFS-9079.01.patch, HDFS-9079.02.patch, HDFS-9079.03.patch, HDFS-9079.04.patch,
HDFS-9079.05.patch, HDFS-9079.06.patch, HDFS-9079.07.patch, HDFS-9079.08.patch, HDFS-9079.09.patch,
HDFS-9079.10.patch, HDFS-9079.11.patch, HDFS-9079.12.patch, HDFS-9079.13.patch, HDFS-9079.14.patch,
HDFS-9079.15.patch, HDFS-9079-HDFS-7285.00.patch
>
>
> A non-striped DataStreamer goes through the following steps in error handling:
> {code}
> 1) Finds error => 2) Asks NN for new GS => 3) Gets new GS from NN => 4) Applies
new GS to DN (createBlockOutputStream) => 5) Ack from DN => 6) Updates block on NN
> {code}
> With multiple streamer threads run in parallel, we need to correctly handle a large number
of possible combinations of interleaved thread events. For example, {{streamer_B}} starts
step 2 in between events {{streamer_A.2}} and {{streamer_A.3}}.
> HDFS-9040 moves steps 1, 2, 3, 6 from streamer to {{DFSStripedOutputStream}}. This JIRA
proposes some further optimizations based on HDFS-9040:
> # We can preallocate GS when NN creates a new striped block group ({{FSN#createNewBlock}}).
For each new striped block group we can reserve {{NUM_PARITY_BLOCKS}} GS's. If more than {{NUM_PARITY_BLOCKS}}
errors have happened we shouldn't try to further recover anyway.
> # We can use a dedicated event processor to offload the error handling logic from {{DFSStripedOutputStream}},
which is not a long running daemon.
> # We can limit the lifespan of a streamer to be a single block. A streamer ends either
after finishing the current block or when encountering a DN failure.
> With the proposed change, a {{StripedDataStreamer}}'s flow becomes:
> {code}
> 1) Finds DN error => 2) Notify coordinator (async, not waiting for response) =>
terminates
> 1) Finds external error => 2) Applies new GS to DN (createBlockOutputStream) =>
3) Ack from DN => 4) Notify coordinator (async, not waiting for response)
> {code}



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

---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org


Mime
View raw message