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https://issues.apache.org/jira/browse/HDFS-9924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15187193#comment-15187193
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Bob Hansen commented on HDFS-9924:
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We are currently implementing a native C++ asynchronous API for HDFS under the
HDFS-8707 umbrella. While I don't see tremendous value in making them
equivalent, perhaps there are some lessons learned that could translate.
Futures are a good match for the use case where the consumer wants to kick of a
multitude of async requests and wait until they are all done to make progress,
but we've found that there are also compelling use cases where you want a small
amount of logic and further async I/O in a completion handler, so I might
recommend supporting both Future-based results as well as callback-based
results.
> [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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