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https://issues.apache.org/jira/browse/HDFS-13767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16568843#comment-16568843
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Chen Liang commented on HDFS-13767:
-----------------------------------
Thanks for comments [~zero45].
bq. (2) A concern about the unit test...
Thanks for trying this. I think it might be related to the recent update that
enabled in-progress edit tail. Because if I disable in-progress edit tail for
this test, then add the delay you mentioned, the test will succeed, but took
longer (expected). I will need to look deeper to see how in-progress edit tail
worked with this. [~xkrogen] any fast insights on this?
bq. (3) So far these patches don't actually ...
The only reason there is msync in {{NameNodeRpcServer}} is because msync is
part of {{ClientProtocol}}, and NameNodeRpcServer implements it. So changing
this in NameNodeRpcServer won't compile. I guess msync is a little bit
different from other RPC calls, in that from client side, it's another RPC call
like others, but from server side, all it's logic is handled in RPC layer, not
in NN layer at all.
bq. (4) I was curious about making msync pause ...
Just some thoughts of mine: it is true that there will be no deferred call in
this case, but seems to me this will also add retry msync calls, so I don't see
a particular advantage here in terms of call queue load. Actually it maybe even
worse: if client times out and retries, the previous call could still be in the
server call queue? In which case we could have multiple msync call in the
server call queue, many clients doing this msync retry could fill up the queue
unnecessarily. While if the client retry interval is long, it can easily be
just wasting time.
> Add msync server implementation.
> --------------------------------
>
> Key: HDFS-13767
> URL: https://issues.apache.org/jira/browse/HDFS-13767
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Chen Liang
> Assignee: Chen Liang
> Priority: Major
> Attachments: HDFS-13767-HDFS-12943.001.patch,
> HDFS-13767-HDFS-12943.002.patch, HDFS-13767.WIP.001.patch,
> HDFS-13767.WIP.002.patch, HDFS-13767.WIP.003.patch, HDFS-13767.WIP.004.patch
>
>
> This is a followup on HDFS-13688, where msync API is introduced to
> {{ClientProtocol}} but the server side implementation is missing. This is
> Jira is to implement the server side logic.
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