hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Sean Busbey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-11644) Support for querying outputstream capabilities
Date Wed, 02 Aug 2017 03:36:03 GMT

    [ https://issues.apache.org/jira/browse/HDFS-11644?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16110224#comment-16110224
] 

Sean Busbey commented on HDFS-11644:
------------------------------------

We need docs on using this feature. I'd like to file a blocker on HBase 2.0 to make use of
it where it is present, specifically so that we can avoid deploying the HBase WAL on filesystems
that don't support hflush/hsync (such as EC). The lack of ability to reliably flush/sync doesn't
appear to be called out in the Erasure Coding docs as a concern for those who might deploy
it and I'd rather HBase bring the risk to operators' attention by failing fast when it finds
the configuration.

But I can't find any guidance on using this feature (or that it exists) in the 3.0.0-alpha4
release notes nor in the filesystem docs.  I also can't tell from the javadocs on StreamCapabilities
what I'm even supposed to query for to check on the fundamentals that this jira is addressing
(hflush / hsync).

> Support for querying outputstream capabilities
> ----------------------------------------------
>
>                 Key: HDFS-11644
>                 URL: https://issues.apache.org/jira/browse/HDFS-11644
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: erasure-coding
>    Affects Versions: 3.0.0-alpha1
>            Reporter: Andrew Wang
>            Assignee: Manoj Govindassamy
>              Labels: hdfs-ec-3.0-must-do
>             Fix For: 2.9.0, 3.0.0-alpha4
>
>         Attachments: HDFS-11644.01.patch, HDFS-11644.02.patch, HDFS-11644.03.patch, HDFS-11644-branch-2.01.patch
>
>
> FSDataOutputStream#hsync checks if a stream implements Syncable, and if so, calls hsync.
Otherwise, it just calls flush. This is used, for instance, by YARN's FileSystemTimelineWriter.
> DFSStripedOutputStream extends DFSOutputStream, which implements Syncable. However, DFSStripedOS
throws a runtime exception when the Syncable methods are called.
> We should refactor the inheritance structure so DFSStripedOS does not implement Syncable.



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

---------------------------------------------------------------------
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