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https://issues.apache.org/jira/browse/HBASE-13907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14625740#comment-14625740
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Sean Busbey commented on HBASE-13907:
-------------------------------------
{code}
+ ... This behavior
+ is not expected to change. Alternately, you can include the coprocessor
version in its
+ classname. This way you can unload the old coprocessor and load the new one,
+ without restarting the RegionServer. However, the old version will remain in
memory,
+ so this solution is a temporary one, and restarting will eventually be
necessary.
{code}
This currently works? Are we still loading additional jars at runtime for
Coprocessors? Folks who are running coprocessors are already kind of down a
dark path, but should we encourage the cleaner "rolling restart of region
servers" to reduce the changes we have to debug classloader pain?
{code}
+Coprocessor Logging::
+ The Coprocessor framework does not provide an API for logging beyond
standard Java
+ logging. You can log to the location specified in the system property
`HBASE_LOG_DIR`,
+ which is set in the RegionServer's `hbase-env.sh` file.
{code}
Won't using commons-logging or slf4j work? What do we gain by having them
attempt to log direclty to this directory instead of just using the same
logging framework we use?
{code}
+Coprocessor Configuration::
+ If you do not want to load coprocessors from the HBase Shell, you can add
their configuration
+ properties to `hbase-site.xml`. In <<load_coprocessor_in_shell>>, two
arguments are
+ set: `arg1=1,arg2=2`. These could have been added to `hbase-site.xml` as
follows:
{code}
just for my own clarity, if they use the hbase-site.xml approach then admins
loading the coprocessor in the shell won't be able to override the arguments,
right? We should mention, either way.
> Document how to deploy a coprocessor
> ------------------------------------
>
> Key: HBASE-13907
> URL: https://issues.apache.org/jira/browse/HBASE-13907
> Project: HBase
> Issue Type: Bug
> Components: documentation
> Reporter: Misty Stanley-Jones
> Assignee: Misty Stanley-Jones
> Attachments: HBASE-13907-1.patch, HBASE-13907-2.patch,
> HBASE-13907.patch
>
>
> Capture this information:
> > Where are the dependencies located for these classes? Is there a path on
> > HDFS or local disk that dependencies need to be placed so that each
> > RegionServer has access to them?
> It is suggested to bundle them as a single jar so that RS can load the whole
> jar and resolve dependencies. If you are not able to do that, you need place
> the dependencies in regionservers class path so that they are loaded during
> RS startup. Do either of these options work for you? Btw, you can load the
> coprocessors/filters into path specified by hbase.dynamic.jars.dir [1], so
> that they are loaded dynamically by regionservers when the class is accessed
> (or you can place them in the RS class path too, so that they are loaded
> during RS JVM startup).
> > How would one deploy these using an automated system?
> > (puppet/chef/ansible/etc)
> You can probably use these tools to automate shipping the jars to above
> locations?
> > Tests our developers have done suggest that simply disabling a coprocessor,
> > replacing the jar with a different version, and enabling the coprocessor
> > again does not load the newest version. With that in mind how does one know
> > which version is currently deployed and enabled without resorting to
> > parsing `hbase shell` output or restarting hbase?
> Actually this is a design issue with current classloader. You can't reload a
> class in a JVM unless you delete all the current references to it. Since the
> current JVM (classloader) has reference to it, you can't overwrite it unless
> you kill the JVM, which is equivalent to restarting it. So you still have the
> older class loaded in place. For this to work, classloader design should be
> changed. If it works for you, you can rename the coprocessor class name and
> the new version of jar and RS loads it properly.
> > Where does logging go, and how does one access it? Does logging need to be
> > configured in a certain way?
> Can you please specify which logging you are referring to?
> > Where is a good location to place configuration files?
> Same as above, are these hbase configs or something else? If hbase configs,
> are these gateway configs/server side?
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