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https://issues.apache.org/jira/browse/HDFS-5366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13820361#comment-13820361
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Colin Patrick McCabe commented on HDFS-5366:
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bq. Since we already have a config key named
"dfs.namenode.path.based.cache.refresh.interval.ms", can we call this one
"dfs.namenode.path.based.cache.retry.interval.ms"?
yeah, I like that name better
bq. New configs should go in hdfs-default.xml too
ok
bq. Nit: extra newline in DatanodeManager#getCacheCommand
ok
bq. Javadoc on DatanodeDescriptor methods saying whether they take wallclock or
monotonic time
ok
bq. Any reason to prefer the iterator-based removal over using clear? If it's
not necessary, we could not do this to keep the diff small.
This way, we only have to iterate over it once, not twice.
bq. Extra imports in CacheReplicationMonitor, DatanodeDescriptor
ok
bq. In DatanodeManager, having variables named sendingCachingCommands and
sendCachingCommands is confusing, rename to retryCachingCommands or something?
renamed to {{shouldSendCachingCommands}}
> 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
>
>
> 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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