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https://issues.apache.org/jira/browse/HAMA-966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14639891#comment-14639891
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Edward J. Yoon commented on HAMA-966:
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Hi,
Here's some background for you. Basically, each BSP task starts RPC server for
communication among other tasks. If 'bsp.tasks.maximum' is 3, then GroomServer
of Hama framework launches maximum 3 tasks per node. By default, they uses
assigned port numbers 61000, 61001, and 61002 from GroomServer. When
startServer() method is called, we checks whether assigned port is available or
not once more. Because, there are occasionally binding problems with abnormally
crashed zombie tasks from previous job.
As you mentioned, it should be considered an RPC server start failure and an
exception should be thrown. I love Option 2. Question is that only
BindException can be occurred.
> NioServerListener doesn't throw any exceptions.
> -----------------------------------------------
>
> Key: HAMA-966
> URL: https://issues.apache.org/jira/browse/HAMA-966
> Project: Hama
> Issue Type: Bug
> Components: bsp core
> Affects Versions: 0.7.0
> Reporter: JongYoon Lim
>
> *NioServerListener* which extends *Thread* can't throw any exceptions because
> it swallows them in *run()* as follows.
> {code:java}
> try {
> // code for server bootstraping and binding
> } catch (Exception e) {
> e.printStackTrace();
> }
> {code}
> This results in that *startServer()* can't catch *BindException* and retry to
> start the server recursively. There can be two options.
> * Option 1. Use *Thread.UncaughtExceptionHandler*.
> * Option 2. Make *NioServerListener* extend *Callable* and use *get()* of
> *Future* to catch exceptions.
> I think *Option 2* looks better because the code could be more intuitive.
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