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https://issues.apache.org/jira/browse/HDFS-7758?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lei (Eddy) Xu updated HDFS-7758:
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Attachment: HDFS-7758.004.patch
Thanks a lot for detailed review, [~cmccabe]. Sorry for updating this late.
bq. Instead of ReferredFsVolumeList, how about calling the class FsVolumeRefs?
I changed it to {{ReferredFsVolumes}}. Because I'd like to give people an
impression that this is a collection of {{FsVolume}}, as they can run:
{code}
for (FsVolumeSpi volume : referredVolumes)
// or
FsVolumeSpi volume = referredVolumes.get(123)
{code}
No internal {{FsVolumeReference}} is exposed through this class.
bq. This looks like a bugfix, separate from this code cleanup.
Done
bq. What's the motivation for switching from an interface to an abstract class?
This was because I added {{FsVolumeReference#releaseVolumes()}}. Now I changed
it back after this function is removed.
bq. Why do we need both ReferredFsVolumeListImpl and ReferredFsVolumeList?
Done. Only {{ReferredFsVolumes}} now.
Thanks again!
> Retire FsDatasetSpi#getVolumes() and use FsDatasetSpi#getVolumeRefs() instead
> -----------------------------------------------------------------------------
>
> Key: HDFS-7758
> URL: https://issues.apache.org/jira/browse/HDFS-7758
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Affects Versions: 2.6.0
> Reporter: Lei (Eddy) Xu
> Assignee: Lei (Eddy) Xu
> Attachments: HDFS-7758.000.patch, HDFS-7758.001.patch,
> HDFS-7758.002.patch, HDFS-7758.003.patch, HDFS-7758.004.patch
>
>
> HDFS-7496 introduced reference-counting the volume instances being used to
> prevent race condition when hot swapping a volume.
> However, {{FsDatasetSpi#getVolumes()}} can still leak the volume instance
> without increasing its reference count. In this JIRA, we retire the
> {{FsDatasetSpi#getVolumes()}} and propose {{FsDatasetSpi#getVolumeRefs()}}
> and etc. method to access {{FsVolume}}. Thus it makes sure that the consumer
> of {{FsVolume}} always has correct reference count.
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