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https://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12554440
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stack commented on HADOOP-1700:
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Ruyue:
I know little of hdfs internals but here are a few comments on the patch.
Looks like you made your patch with diff going between a java-old and a
java-new directory. Can you makie it instead by doing a 'svn diff' inside the
top directory of an hadoop checkout? You should also make the patch apply to
TRUNK. Currently it does not. Its unlikely that your patch will be added to
the 0.15.x branch since usually only bug fixes are made against released
versions and as is, it makes it hard for me to take your patch for a test drive.
Tabs should be purged and replaced by spaces to make your patch palatable.
New classes could do with javadoc explaining their purpose: e.g.
BasicAppendInfo class comment could explain where its used and the payload it
carries.
New methods added to the protocol could also do with javadoc: e.g.
baseAppendFile. Also, I'd guess that as is, your patch will emit javadoc
warnings which will make it so your patch will fail the patch-build (your
createFile method does not detail the method parameters). You also have an
instance of empty javadoc.
Your getting of blockid is synchronized but not on setting.
> Append to files in HDFS
> -----------------------
>
> Key: HADOOP-1700
> URL: https://issues.apache.org/jira/browse/HADOOP-1700
> Project: Hadoop
> Issue Type: New Feature
> Components: dfs
> Affects Versions: 0.15.1
> Reporter: stack
> Attachments: append.patch, Appends.doc, Appends.doc, Appends.html
>
>
> Request for being able to append to files in HDFS has been raised a couple of
> times on the list of late. For one example, see
> http://www.nabble.com/HDFS%2C-appending-writes-status-tf3848237.html#a10916193.
> Other mail describes folks' workarounds because this feature is lacking:
> e.g. http://www.nabble.com/Loading-data-into-HDFS-tf4200003.html#a12039480
> (Later on this thread, Jim Kellerman re-raises the HBase need of this
> feature). HADOOP-337 'DFS files should be appendable' makes mention of file
> append but it was opened early in the life of HDFS when the focus was more on
> implementing the basics rather than adding new features. Interest fizzled.
> Because HADOOP-337 is also a bit of a grab-bag -- it includes truncation and
> being able to concurrently read/write -- rather than try and breathe new life
> into HADOOP-337, instead, here is a new issue focused on file append.
> Ultimately, being able to do as the google GFS paper describes -- having
> multiple concurrent clients making 'Atomic Record Append' to a single file
> would be sweet but at least for a first cut at this feature, IMO, a single
> client appending to a single HDFS file letting the application manage the
> access would be sufficent.
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