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https://issues.apache.org/jira/browse/HADOOP-9160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13725608#comment-13725608
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Luke Lu commented on HADOOP-9160:
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bq. I'm surprised they speak Jolokia but not HTTP.
They speak JMX and/or HTTP with java builtin http server (not servlet), which
are not amenable for servlet filters (for SPNEGO etc.) that we have.
Customers/users wish/want to use these monitoring/tuning agents they already
have with the auth mechanisms that hadoop already has. Jolokia can provide a
great out-of-the-box experience.
bq. Similarly, I'd like to understand whether, in your ideal world, you could,
say, read a file or call "hdfs upgrade" over JMX?
In an ideal world, JMX/Jolokia being a JVM builtin management mechanism can be
used to manage any application component without restarting the server JVM to
minimize service downtime. The current metrics system is already restartable
for different configs via JMX without server restart. It could certainly read a
status/log file and/or do an hdfs upgrade if needed. Though short term, we only
plan to expose a small set of admin functions related to resource management.
bq. We've spent considerable effort getting backwards-compatible protocols,
Opening up another layer of RPC exposes us to more issues here.
JMX/Jolokia are even more backward compatible friendly as they natively support
attribute/method reflection/introspection without the need of IDLs or any
specific client libraries, which is great for interoperability. Please see the
section of interoperability in my previous comment for more details.
Technically JMX is not another layer of RPC but the JVM native management
mechanism that could in theory manage the Hadoop RPC subsystem as well.
> Adopt Jolokia as the JMX HTTP/JSON bridge.
> ------------------------------------------
>
> Key: HADOOP-9160
> URL: https://issues.apache.org/jira/browse/HADOOP-9160
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Luke Lu
> Assignee: Junping Du
> Labels: features
> Attachments: hadoop-9160-demo-branch-1.txt, HADOOP-9160.patch
>
>
> The current JMX HTTP bridge has served its purpose, while a more complete
> solution: Jolokia (formerly Jmx4Perl) has been developed/matured over the
> years.
> Jolokia provides comprehensive JMX features over HTTP/JSON including search
> and list of JMX attributes and operations metadata, which helps to support
> inter framework/platform compatibility. It has first class language bindings
> for Perl, Python, Javascript, Java.
> It's trivial (see demo patch) to incorporate Jolokia servlet into Hadoop HTTP
> servers and use the same security mechanisms.
> Adopting Jolokia will substantially improve the manageability of Hadoop and
> its ecosystem.
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