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Xiaobing Zhou commented on HDFS-9924: ------------------------------------- {quote} With your solution, you will block on request 1 for a long time before resubmit the failed 2-99 request. This is a inherent defect of lacking the support of callback. And a better solution is, sorry, but again, using multiple threads With a thread pool and CompletionService, you can (sometimes) get the failed request first. {quote} You just had an extreme example trying to establish cause and effect. If it's really the case, why not to resort to Future#IsDone() or call Future#get(long timeout, TimeUnit unit) with neglectable timeout? You don't have to be blocked to send failed requests earlier. In addition, the RPC layer is async as is, Connection#receiveRpcResponse is run by a thread (i.e. Connection extends Thread) to actively buffer the final result into Client#Call as long as it's available on socket. As a result, The final result is already available in Client#Call most often. You will not be experiencing the block subject to Future#get unless the result is not returned by server. Thank you anyway for the comments. > [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. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org