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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9924) [umbrella] Asynchronous HDFS Access
Date Thu, 10 Mar 2016 23:43:41 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15190179#comment-15190179
] 

Steve Loughran commented on HDFS-9924:
--------------------------------------

So the use cases are one or more rename/delete operations to be fired at the NN, with a sync
notifications as they complete? Other things: stat(), getBlockLocations, open(), aren't considered
operations you would want to do? I concur, though a copy op would be nice to have 

But do we need async calls, or could we do something like {{Future<> exec(List<operations>)}}
and the NN given a list of actions for it to execute, ideally in order? As that would be one
RPC, and perhaps, if locks were held over opts, efficiently. 

Was something like that considered?

> [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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