[
https://issues.apache.org/jira/browse/HDFS-7430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14254474#comment-14254474
]
Colin Patrick McCabe commented on HDFS-7430:
--------------------------------------------
So, I changed the rate calculation a bit. Now it simply scans at the
configured bytes per second the average bytes per second in the last hour is
lower than the target, and scans nothing if not. I was having some trouble
getting the rate calculation to be exactly what I wanted (It's kind of a PID
control problem), so I think a fixed rate is easier to understand. Added a
unit test for this as well.
> Refactor the BlockScanner to use O(1) memory and use multiple threads
> ---------------------------------------------------------------------
>
> Key: HDFS-7430
> URL: https://issues.apache.org/jira/browse/HDFS-7430
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.7.0
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-7430.002.patch, HDFS-7430.003.patch,
> HDFS-7430.004.patch, HDFS-7430.005.patch, HDFS-7430.006.patch,
> HDFS-7430.007.patch, memory.png
>
>
> We should update the BlockScanner to use a constant amount of memory by
> keeping track of what block was scanned last, rather than by tracking the
> scan status of all blocks in memory. Also, instead of having just one
> thread, we should have a verification thread per hard disk (or other volume),
> scanning at a configurable rate of bytes per second.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
