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From James Hughes <jn...@virginia.edu>
Subject Re: java.lang.NoClassDefFoundError with fields of custom Filter
Date Thu, 07 Jul 2016 17:27:44 GMT
Hi Massimiliano,

I'm a fan of producing uber jars for this kind of thing; we do that for
GeoMesa.  There is one gotcha which can come up:  if you have several uber
jars in lib/ext, they can collide in rather unexpected ways.

There are two options to call out:

First, Accumulo has support for loading jars from HDFS into namespaces.
With that, you could have various namespaces for different versions or
different collections of iterator projects.  If you are sharing a dev cloud
with other projects or co-workers working on the same project that can be
helpful since it would avoid restarts, etc.  Big thumbs-up for this
approach!

Second, rather than having an uber jar, you could build up zip files with
the various jars you need for your iterators and unzip them in lib/ext.  If
you did that for multiple competing iterator projects, you'd avoid
duplication of code inside uber-jars.  Also, you'd be able to see if there
are 8 versions of Log4J and Guava in lib/ext...;)  It wouldn't be as
powerful as the namespace, but there's something nice about having a
low-tech approach.

Others will likely have varied experiences; I'm not sure if there's an
established 'best practice' here.

Cheers,

Jim

On Thu, Jul 7, 2016 at 12:56 PM, Massimilian Mattetti <MASSIMIL@il.ibm.com>
wrote:

> Thanks for your prompt response, you are right Jim. There is a static
> dependency to Log4J in my lexicoder. Adding the Log4J Jar to the classpath
> solved the problem.
> Would you suggest to use an Uber Jar to avoid this kind of problems?
>
> Regards,
> Massimiliano
>
>
>
>
> From:        James Hughes <jnh5y@virginia.edu>
> To:        user@accumulo.apache.org
> Date:        07/07/2016 06:25 PM
> Subject:        Re: java.lang.NoClassDefFoundError with fields of custom
> Filter
> ------------------------------
>
>
>
> Hi Massimilian,
>
> As a quick note, your error says that it could not initialize class
> accumulo.lexicoders.MyLexicoder.  Did you provide all the dependencies for
> your class on Accumulo's classpath?
>
> That exception (or similar) can occur if there is a static block in your
> MyLexicoder class which can't run properly.
>
> Cheers,
>
> Jim
>
>
> On Thu, Jul 7, 2016 at 11:19 AM, Massimilian Mattetti <
> *MASSIMIL@il.ibm.com* <MASSIMIL@il.ibm.com>> wrote:
> Hi,
>
> I have implemented a custom filter and a custom lexicoder. Both this two
> classes are packed in the same jar that has been deployed under the
> directory $ACCUMULO_HOME/*lib*/*ext*of my Accumulo servers (version
> 1.7.1). The lexicoder is used by the filter to get the real object from the
> accumulo value and test some conditions on it. When I tried to scan the
> table applying this filter I got the following exception:
>
> Caused by: java.lang.NoClassDefFoundError: Could not initialize class
> accumulo.lexicoders.MyLexicoder
>         at accumulo.filters.MyFilter.<init>(MyFilter.java:24)
>         at sun.reflect.GeneratedConstructorAccessor9.newInstance(Unknown
> Source)
>         at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
>         at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
>         at java.lang.Class.newInstance(Class.java:442)
>         at
> org.apache.accumulo.core.iterators.IteratorUtil.loadIterators(IteratorUtil.java:261)
>         at
> org.apache.accumulo.core.iterators.IteratorUtil.loadIterators(IteratorUtil.java:237)
>         at
> org.apache.accumulo.core.iterators.IteratorUtil.loadIterators(IteratorUtil.java:218)
>         at
> org.apache.accumulo.core.iterators.IteratorUtil.loadIterators(IteratorUtil.java:205)
>         at
> org.apache.accumulo.tserver.tablet.ScanDataSource.createIterator(ScanDataSource.java:193)
>         at
> org.apache.accumulo.tserver.tablet.ScanDataSource.iterator(ScanDataSource.java:127)
>         at
> org.apache.accumulo.core.iterators.system.SourceSwitchingIterator.seek(SourceSwitchingIterator.java:180)
>         at
> org.apache.accumulo.tserver.tablet.Tablet.nextBatch(Tablet.java:880)
>         at org.apache.accumulo.tserver.tablet.Scanner.read(Scanner.java:98)
>         at
> org.apache.accumulo.tserver.scan.NextBatchTask.run(NextBatchTask.java:69)
>         at
> org.apache.htrace.wrappers.TraceRunnable.run(TraceRunnable.java:57)
>         ... 4 more
>
>
>  I do not undestand how it is possible that the class loader is able to
> find the filter and no the lexicoder. Am I missing something?
>
> Thanks,
> Massimiliano
>
>
>
>
>

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