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https://issues.apache.org/jira/browse/HADOOP-3628?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-3628:
-----------------------------------
Attachment: hadoop-3628.patch
This updated patch
-should address the (over-cautious) findbugs warnings
-includes the task tracker in the service lifecycle
-adds a mock service and test class to go alongside, verifying that the
expected lifecycle is followed.
-uses STARTED and LIVE as its states to transit through when starting.
Based on the mock service tests, I've tweaked the ping() operation to
* ignore ping() requests when starting up
* call an innerPing() method when ping() is called when LIVE; this is for
subclasses to add health checks
* automatically go into FAILED state when innerPing() throws an exception.
So: if your liveness test fails, that service is deemed to have failed.
I'm using this downstream, it works fairly well.
Let's see what hudson makes of it.
> Add a lifecycle interface for Hadoop components: namenodes, job clients, etc.
> -----------------------------------------------------------------------------
>
> Key: HADOOP-3628
> URL: https://issues.apache.org/jira/browse/HADOOP-3628
> Project: Hadoop Core
> Issue Type: Improvement
> Components: dfs, mapred
> Affects Versions: 0.19.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Attachments: AbstractHadoopComponent.java, hadoop-3628.patch,
> hadoop-3628.patch, hadoop-3628.patch, hadoop-3628.patch, hadoop-3628.patch,
> hadoop-3628.patch
>
>
> I'd like to propose we have a standard interface for hadoop components, the
> things that get started or stopped when you bring up a namenode. currently,
> some of these classes have a stop() or shutdown() method, with no standard
> name/interface, but no way of seeing if they are live, checking their health
> of shutting them down reliably. Indeed, there is a tendency for the spawned
> threads to not want to die; to require the entire process to be killed to
> stop the workers.
> Having a standard interface would make it easier for
> * management tools to manage the different things
> * monitoring the state of things
> * subclassing
> The latter is interesting as right now TaskTracker and JobTracker start up
> threads in their constructor; that's very dangerous as subclasses may have
> their methods called before they are full initialised. Adding this interface
> would be the right time to clean up the startup process so that subclassing
> is less risky.
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