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https://issues.apache.org/jira/browse/HDFS-9924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15330173#comment-15330173
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stack commented on HDFS-9924:
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bq. There are multiple comments from both sides indicating that
CompletableFuture is the ideal option for 3.x.
[~arpiagariu] Please leave off concluding a discussion that is still ongoing
(CF is not 'ideal' and is not a given). It doesn't help sir.
bq. You mean just like we recently added 'avoid local nodes' because another
downstream component wanted to try it?
You misrepresent, again. HBase ran for years with a workaround while waiting on
the behavior to show up in HDFS; i.e. the hbase project did not have an
'interest' in 'avoid local nodes'; they required this behavior of the
filesystem and ran with a suboptimal hack until it showed up.
In this case all we have is 'interest' and requests for technical justification
go unanswered.
bq. The Hive engineers think they can make it work for them and there was a
compromise proposed to introduce the API as unstable.
I'm interested in how Hive will do async w/ only a Future and in how this
suboptimal API in particular will solve their issue (is it described
anywhere?). In my experience, a bunch of rigging (threads) for polling, rather
than notification, is required when all you have is a Future to work with.
> [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
> Attachments: AsyncHdfs20160510.pdf
>
>
> 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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