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https://issues.apache.org/jira/browse/HDFS-5431?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13849744#comment-13849744
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Andrew Wang commented on HDFS-5431:
-----------------------------------
Thanks for the reviews, v6 attached. Changes are only to CRM, so you can just
review that.
I thought about it, and went way back to the condition variable proposal. I got
rid of the object lock, favoring a new CRM lock with two cvars and some status
variables. The synchronization here is unfortunately still kind of complicated,
but I think overall more better.
I also want to note this isn't actually read-after-write consistency since the
{{wait}} methods just wait for the scan count to advance, not for all pending
updates to be flushed. I think this could be fixed (basically, if a scan is
ongoing and CRM is dirty, wait for scanCount to advance by 2 rather than 1),
but as this is also a performance tradeoff, I'd really like to just get this
committed and fix it later if necessary.
I also re-examined {{close}} since I was re-doing the synchronization. This
snippet looks like it makes the thread calling {{close}} wait for 60 seconds,
where the intent is probably to interrupt the CRM thread and make it cleanly
exit:
{code}
try {
if (this.isAlive()) {
this.join(60000);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
{code}
If you agree, I'll file a follow-on to fix this up. It could affect HA state
transitions.
> support cachepool-based limit management in path-based caching
> --------------------------------------------------------------
>
> Key: HDFS-5431
> URL: https://issues.apache.org/jira/browse/HDFS-5431
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, namenode
> Affects Versions: 3.0.0
> Reporter: Colin Patrick McCabe
> Assignee: Andrew Wang
> Attachments: hdfs-5431-1.patch, hdfs-5431-2.patch, hdfs-5431-3.patch,
> hdfs-5431-4.patch, hdfs-5431-5.patch, hdfs-5431-6.patch
>
>
> We should support cachepool-based limit management in path-based caching.
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