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https://issues.apache.org/jira/browse/HDFS-5366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13820755#comment-13820755
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Andrew Wang commented on HDFS-5366:
-----------------------------------
+1, looks basically good. Just a few notes:
* The mlock stubbing will need to be rebased a bit for HDFS-5450 which was just
committed, since it was still stubbing with MappableBlock#Mlocker.
* There was also a fix to TestFsDatasetCache to reset the Mlocker stub to the
default after it's set, will want the same thing here.
* We probably want to stub mlock for TestPathBasedCacheRequests too, but I feel
like we should leave at least one test calling mlock. Maybe in TestNativeIO?
> recaching improvements
> ----------------------
>
> Key: HDFS-5366
> URL: https://issues.apache.org/jira/browse/HDFS-5366
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Affects Versions: 3.0.0
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-5366-caching.001.patch, HDFS-5366.002.patch,
> HDFS-5366.005.patch, HDFS-5366.006.patch
>
>
> There are a few things about our HDFS-4949 recaching strategy that could be
> improved.
> * We should monitor the DN's maximum and current mlock'ed memory consumption
> levels, so that we don't ask the DN to do stuff it can't.
> * We should not try to initiate caching on stale or decomissioning DataNodes
> (although we should not recache things stored on such nodes until they're
> declared dead).
> * We might want to resend the {{DNA_CACHE}} or {{DNA_UNCACHE}} command a few
> times before giving up. Currently, we only send it once.
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