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https://issues.apache.org/jira/browse/HDFS-9643?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Clampffer updated HDFS-9643:
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Attachment: HDFS-9643.HDFS-8707.000.patch
Initial patch, I've manually tested it but need to sort out the failures hidden
by HDFS-9610 before I can write decent unit tests.
Open questions:
-Right now the cancel logic is added directly to each continuation in the
remote block reader. On one hand this is simple and works, on the other it's
boilerplate code. Is this worth pushing into the continuation pipeline code at
the moment? I think it's worth keeping it simple until NN operations become
cancelable.
-In this implementation FileHandle::CancelOperations is irreversible and
prevents it from being used again. Can anyone think of a reason not to have it
also close the file or at least clear vector<LocatedBlockProto>?
-Should the FileHandle have a callback when it knows that there are no pending
operations? Should be possible to just check the reference count on the
CancelHandle to verify.
> libhdfs++: Support async cancellation of read operations
> --------------------------------------------------------
>
> Key: HDFS-9643
> URL: https://issues.apache.org/jira/browse/HDFS-9643
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Reporter: James Clampffer
> Assignee: James Clampffer
> Attachments: HDFS-9643.HDFS-8707.000.patch
>
>
> It should be possible for any thread to cancel operations in progress on a
> FileHandle. Any ephemeral objects created by the FileHandle should free
> resources as quickly as possible.
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