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https://issues.apache.org/jira/browse/HDFS-8332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14545800#comment-14545800
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Chris Nauroth commented on HDFS-8332:
-------------------------------------
This is very strange. It appears that this only "worked" because the RPC proxy
is still operable even after calling {{RPC#stopProxy}} inside
{{DFSClient#closeConnectionToNamenode}}. This is not what I would have
expected. I thought that this patch by calling {{checkOpen}} consistently just
changed a failure to give a more descriptive error.
This is going to be a gray area for compatibility. Code that uses a
{{FileSystem}} after closing it is incorrect code. Many operations already
fail fast. We might be within the letter of the law for the compatibility
policy by making this change, but there is an argument that callers could be
dependent on the existing bug.
In this kind of situation, I like to consider if the risks outweigh the
benefits. This change isn't an absolute requirement to fix a critical bug or
ship a new feature. Considering that, I think a conservative approach would be
to re-target this patch to trunk/3.0.0 and revert from branch-2. We can set
the incompatible flag and enter a release note for 3.0.0 stating that callers
who were dependent on the buggy behavior must fix their code when upgrading.
What do others think of this?
Also, I'd like to suggest that we change pre-commit to trigger
hadoop-hdfs-httpfs tests automatically for all hadoop-hdfs patches. We've seen
problems like this in the past. hadoop-hdfs-httpfs gets patched so
infrequently that it's easy to miss it when a hadoop-hdfs change introduces a
test failure. As a practical matter, we might not be able to add those tests
until the current HDFS test runs get optimized.
> DFS client API calls should check filesystem closed
> ---------------------------------------------------
>
> Key: HDFS-8332
> URL: https://issues.apache.org/jira/browse/HDFS-8332
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Rakesh R
> Assignee: Rakesh R
> Fix For: 2.8.0
>
> Attachments: HDFS-8332-000.patch, HDFS-8332-001.patch,
> HDFS-8332-002-Branch-2.patch, HDFS-8332-002.patch,
> HDFS-8332.001.branch-2.patch
>
>
> I could see {{listCacheDirectives()}} and {{listCachePools()}} APIs can be
> called even after the filesystem close. Instead these calls should do
> {{checkOpen}} and throws:
> {code}
> java.io.IOException: Filesystem closed
> at org.apache.hadoop.hdfs.DFSClient.checkOpen(DFSClient.java:464)
> {code}
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