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https://issues.apache.org/jira/browse/HADOOP-3818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12617005#action_12617005
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Rowan Nairn commented on HADOOP-3818:
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bq. For deleting file on exit, we should use FileSystem.deleteOnExit(Path f),
instead of a ShutdownHook.
This doesn't seem to fit my use case. I want to delete an unfinished MapRed
output directory from HDFS *only* if the user terminates the process.
> Not possible to access a FileSystem from within a ShutdownHook
> --------------------------------------------------------------
>
> Key: HADOOP-3818
> URL: https://issues.apache.org/jira/browse/HADOOP-3818
> Project: Hadoop Core
> Issue Type: Bug
> Components: fs
> Affects Versions: 0.17.1
> Reporter: Rowan Nairn
> Priority: Minor
>
> FileSystem uses addShutdownHook to close all FileSystems at exit. This makes
> it impossible to access a FileSystem from within your own ShutdownHook
> threads, say for deleting incomplete output. Using a pre-existing FileSystem
> object is unsafe since it may be closed by the time the thread executes.
> Using FileSystem.get(...) results in an exception:
> Exception in thread "Thread-10" java.lang.IllegalStateException: Shutdown in
> progress
> at java.lang.Shutdown.add(Shutdown.java:81)
> at java.lang.Runtime.addShutdownHook(Runtime.java:190)
> at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1293)
> at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:203)
> at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:108)
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