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https://issues.apache.org/jira/browse/HADOOP-5188?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714675#action_12714675
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Flavio Paiva Junqueira commented on HADOOP-5188:
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Konstantin, Could you be a little more specific on some of your comments? In
particular, the following is not clear to me:
# "But my main concern is that LogDevice (or LoggingDevice) is not the right
abstraction.
And it seems to me that all necessary abstraction are already there you just
need to use them."
You say that all necessary abstraction is there. But, where is "there"? What
abstraction exactly you believe the namenode has currently that enables one to
keep the configuration and properties of a device during the execution of the
namenode? From what Luca is pointing out, it seems that the abstractions you
talk about are still implemented in a way that is very oriented to files, and
LogDevice enables one to abstract away how the log devices behave and are
implemented. Please shed some light on this one.
# "As I said before Edits Streams should be responsible for keeping information
about logging methods. And this is completely orthogonal to the number of
BookKeeper clients you need to instantiate."
I'm not sure what you're trying to say here. What does it mean to keep
information about logging methods? I believe they keep the methods used to
access logs. Now, I agree that the number of bookies that one needs to use is a
separate issue, in the case of BookKeeper concretly. However, we need to
initialize ledgers, and for that we need to remember configuration parameters
for BookKeeper and we need a different initialization procedure. Where should
we keep config parameters for BookKeeper and where should we instantiate and
keep a BookKeeper object?
Also, I agree with your comment on the use of "instanceof".
> Modifications to enable multiple types of logging
> --------------------------------------------------
>
> Key: HADOOP-5188
> URL: https://issues.apache.org/jira/browse/HADOOP-5188
> Project: Hadoop Core
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.20.0
> Reporter: Luca Telloli
> Fix For: 0.21.0
>
> Attachments: HADOOP-5188.patch, HADOOP-5188.patch, HADOOP-5188.patch,
> HADOOP-5188.patch, HADOOP-5188.patch, HADOOP-5188.patch, HADOOP-5188.pdf
>
>
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