[jira] [Commented] (HADOOP-9160) Adopt JMX for management protocols

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-9160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13542554#comment-13542554 ] 

Todd Lipcon commented on HADOOP-9160:
-------------------------------------

I agree with Suresh that I'd rather have the effort put into more/better REST interfaces.

My only fear with offering all these "options" is that the critical daemons get more and more bloated. We might consider a design whereby the critical daemons _only_ expose RPC interfaces, and then we can build separate gateway daemons that expose whatever admin interfaces we want by JMX, HTTP, SNMP, or whatever. Using the plugin infrastructure we already have, those who want to "embed" the gateways in the same process would be welcome to, but it would help keep the core code tight.
                
> Adopt JMX for management protocols
> ----------------------------------
>
>                 Key: HADOOP-9160
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9160
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Luke Lu
>
> Currently we use Hadoop RPC (and some HTTP, notably fsck) for admin protocols. We should consider adopt JMX for future admin protocols, as it's the industry standard for java server management with wide client support.
> Having an alternative/redundant RPC mechanism is very desirable for admin protocols. I've seen in the past in multiple cases, where NN and/or JT RPC were locked up solid due to various bugs and/or RPC thread pool exhaustion, while HTTP and/or JMX worked just fine.
> Other desirable benefits include admin protocol backward compatibility and introspectability, which is convenient for a centralized management system to manage multiple Hadoop clusters of different versions. Another notable benefit is that it's much easier to implement new admin commands in JMX (especially with MXBean) than Hadoop RPC, especially in trunk (as well as 0.23+ and 2.x).
> Since Hadoop RPC doesn't guarantee backward compatibility (probably not ever for branch-1), there are few external tools depending on it. We can keep the old protocols for as long as needed. New commands should be in JMX. The transition can be gradual and backward-compatible.

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