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https://issues.apache.org/jira/browse/HADOOP-8325?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13264354#comment-13264354
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Ravi Prakash commented on HADOOP-8325:
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Hey Tucu! What functionality does this Shutdown Hook Manager provide that the
JVM shutdown hook manager does not?
http://docs.oracle.com/javase/1.4.2/docs/guide/lang/hook-design.html states
bq. The thread can be created in the proper thread group, given the correct
priority, context, and privileges, and so forth.
We can set priorities of the existing shutdown thread and since the JVM uses a
preemptive, priority based scheduling algorithm, they will in essence run in
order of priorities (two threads may have the same priorities but that is
besides the point).
> Add a ShutdownHookManager to be used by different components instead of the
> JVM shutdownhook
> --------------------------------------------------------------------------------------------
>
> Key: HADOOP-8325
> URL: https://issues.apache.org/jira/browse/HADOOP-8325
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.0.0
> Reporter: Alejandro Abdelnur
> Assignee: Alejandro Abdelnur
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HADOOP-8325.patch, HADOOP-8325.patch, HADOOP-8325.patch,
> HADOOP-8325.patch, HADOOP-8325.patch, HADOOP-8325.patch, HADOOP-8325.patch
>
>
> FileSystem adds a JVM shutdown hook when a filesystem instance is cached.
> MRAppMaster also uses a JVM shutdown hook, among other things, the
> MRAppMaster JVM shutdown hook is used to ensure state are written to HDFS.
> This creates a race condition because each JVM shutdown hook is a separate
> thread and if there are multiple JVM shutdown hooks there is not assurance of
> order of execution, they could even run in parallel.
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