hadoop-general mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Scott Carey <sc...@richrelevance.com>
Subject Re: Custom Class Loader for Hadoop M/R jobs?
Date Wed, 14 Apr 2010 17:01:38 GMT
Depending on what the dependency is, you might be able to just remove it from hadoop's lib
directory on your cluster.

For me, Hadoop's later versions has jackson-1.0.1 in its lib directory and that breaks usage
of Avro in a M/R job among other things.  However, the feature that uses this library is unimportant
to me (configuration dump in JSON format) so I just removed the jar.

On Apr 14, 2010, at 6:39 AM, Segel, Mike wrote:

> Hi,
> Ok, here's a bit of a bizarre  issue...
> How do you handle class collisions between Hadoop and your m/r job which calls other
3rd party classes.
> An example: Hadoop has an older version of an open source jar in its /lib directory.
You're interfacing with a 3rd party OS tool that uses a later release of the same jar.
> You can modify the classpath, and that might work. But the better way is to create a
Custom Class Loader. (Non-trivial)
> Looking at the Configuration class, it looks like there are a couple of methods that
deal with loading a class in to the configuration so that the m/r jobs can have access to
them on each node.
> Is this the correct intended use, or am I missing something?
> Has anyone done something like this?
> Thx
> -Mike
> Michael Segel
> Architect,  R&D
> 425 West Randolph Street
> Chicago, IL 60606
> (T)  +1 312-780-3432
> (C)  +1 312-952-8175
> www.navteq.com<http://www.navteq.com/>
> The information contained in this communication may be CONFIDENTIAL and is intended only
for the use of the recipient(s) named above.  If you are not the intended recipient, you are
hereby notified that any dissemination, distribution, or copying of this communication, or
any of its contents, is strictly prohibited.  If you have received this communication in error,
please notify the sender and delete/destroy the original message and any copy of it from your
computer or paper files.

View raw message