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From "Tsz Wo Nicholas Sze (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9924) [umbrella] Asynchronous HDFS Access
Date Tue, 10 May 2016 20:17:12 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15278786#comment-15278786
] 

Tsz Wo Nicholas Sze commented on HDFS-9924:
-------------------------------------------

> However, I am concerned that there has been no design doc posted, but already code committed
to trunk. I am -1 on committing anything more to trunk until we have a design document explaining
how the API will work and what changes it will require in HDFS. ...

The main changes (except the FileSystem API) required in HDFS and Commom are already done.
 It is just some little changes since, as mentioned previously, the underlying RPC mechanism
is already supporting asynchronous calls.  You would easily find it out if you read the code
in more details.

Anyway, I will post a design doc soon as mentioned before.

> [umbrella] Asynchronous HDFS Access
> -----------------------------------
>
>                 Key: HDFS-9924
>                 URL: https://issues.apache.org/jira/browse/HDFS-9924
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>          Components: fs
>            Reporter: Tsz Wo Nicholas Sze
>            Assignee: Xiaobing Zhou
>
> This is an umbrella JIRA for supporting Asynchronous HDFS Access.
> Currently, all the API methods are blocking calls -- the caller is blocked until the
method returns.  It is very slow if a client makes a large number of independent calls in
a single thread since each call has to wait until the previous call is finished.  It is inefficient
if a client needs to create a large number of threads to invoke the calls.
> We propose adding a new API to support asynchronous calls, i.e. the caller is not blocked.
 The methods in the new API immediately return a Java Future object.  The return value can
be obtained by the usual Future.get() method.



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