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https://issues.apache.org/jira/browse/HDFS-11580?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yiqun Lin updated HDFS-11580:
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Attachment: HDFS-11580-HDFS-7240.004.patch
Thanks [~anu], [~vagarychen] and [~msingh] for the great comments! All the
comments make sense to me.
The following are my comments:
1.
{quote}
Do you think we should have 2 functions, like readChunk and readChunkAsync so
that it looks more like java 8-ish ? rather than a boolean flag ?
{quote}
Has addressed this in the latest patch.
2. The problem of that the current async calls still seem like synchronous
calls. Yes, I think this should be a problem here. As [~vagarychen] mentioned,
we should not invoke {{get()}} in the same thread. Maybe we can register a
callback or other way, I take a look into {{CompletableFuture}}, there are
already many APIs we can use for this case. In my latest patch, I used one APIs
named {{CompletableFuture#thenApply}} to deal with the future result
asynchronous and return the new CompletableFuture object. This should be the
right way to return the CompletableFuture object for client and let client to
call future.get().
3.
{quote}
Also because of the async nature of the interface responses, need not be in
the same order as the requests. We will need a method to match the response to
the replies.
{quote}
This is a good catch. If the async interface introduced, we should be more
carefully to get corresponding response of each request. In my latest patch, I
defined a new map to store the pending response. The more details can see in
the method {{XceiverClientHandler#waitForResponse}}.
4.
{quote}
With an async interface, we will always need to keep an eye on the queue depth..
{quote}
Good idea. But I'd like to do this work in another JIRA since current patch
seems a little big now, :).
I have changed many places in the latest patch. Any comment/suggestion are
welcomed.
> Ozone: Support asynchronus client API for SCM and containers
> ------------------------------------------------------------
>
> Key: HDFS-11580
> URL: https://issues.apache.org/jira/browse/HDFS-11580
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ozone
> Affects Versions: HDFS-7240
> Reporter: Anu Engineer
> Assignee: Yiqun Lin
> Attachments: HDFS-11580-HDFS-7240.001.patch,
> HDFS-11580-HDFS-7240.002.patch, HDFS-11580-HDFS-7240.003.patch,
> HDFS-11580-HDFS-7240.004.patch
>
>
> This is an umbrella JIRA that needs to support a set of APIs in Asynchronous
> form.
> For containers -- or the datanode API currently supports a call
> {{sendCommand}}. we need to build proper programming interface and support an
> async interface.
> There is also a set of SCM API that clients can call, it would be nice to
> support Async interface for those too.
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