On Thursday, January 29, 2015 at 9:45:25 AM UTC-8, Sean Corfield wrote:
>
> Which version of Clojure are you using?
>
1.6.0, both for AOT and at runtime.
 

>
> Does clojure-hadoop or Schema include AOT-compiled versions of other 
> libraries and/or core namespaces?
>

No, as far as I know the only AOT compiled code present is clojure-hadoop 
and possibly the Clojure jar itself.  We may depend on other libs that are 
AOT as well, but none that live above schema.  
 

>
> If the answers are 1.7.0 Alpha 5 and "yes" then you've run into the same 
> problem I and a few others did: the previously undefined behavior of 
> loading both AOT and JIT versions of the same code now has a defined 
> behavior (preferring AOT) - and you get this exception.
>

I guess this is probably a different issue then, but maybe there's a common 
workaround?  

Thanks for the quick reply!
 

>
> Sean
>
> On Jan 28, 2015, at 11:39 PM, Jason Wolfe <ja...@w01fe.com <javascript:>> 
> wrote:
>
> First off, I apologize in advance for not having a reduced test case, and 
> express my sincere gratitude in advance for any assistance.  I've been 
> tearing my hair out for a day or so and not making headway, and figured 
> someone here might recognize some keywords and have a pointer in the right 
> direction. (I'm admittedly pretty green when it comes to class loading, and 
> have largely exhausted my google fu).  
>
> *Problem: *
>
> I'm submitting a hadoop job using clojure-hadoop.  All is well with a 
> simple job, but once I require something that transitively depends on 
> Schema, I end up with: 
>
> clojure.lang.Compiler$CompilerException: 
> java.lang.IllegalArgumentException: No implementation of method: :walker of 
> protocol: #'schema.core/Schema found for class: clojure.core$long, 
> compiling:(crane/config.clj:33:4)
>
> It works fine when run in-process with hadoop-mapreduce-client-jobclient, 
> but not with bin/hadoop -jar.  This stunk of a classloader issue, and after 
> digging in it seems that there are multiple versions of clojure.core$long 
> floating around.  The version on which the protocol is extended is not the 
> same class for the fn that the symbol 'long resolves to in client code.
>
> *Context: *
>
> clojure-hadoop is AOT-compiled, and after being loaded by hadoop it 
> dynamically loads the target namespace (not AOT-compiled, nor any other of 
> the code in question) using 
> https://github.com/alexott/clojure-hadoop/blob/master/src/clojure_hadoop/load.clj#L3
>
> From here, schema is transitively required, and then client namespaces 
> attempt to use the Schema protocol to generate validators, and when the 
> schema 'long is used (which resolves to the fn with class 
> clojure.core$long), it fails to find the appropriate method.  
>
> After repeated head-bashing, I've determined that there are (at least two) 
> versions of the clojure.core$long class floating around -- the one used to 
> extend the protocol, which stems from a DynamicClassLoader, and the one 
> that 'long resolves to in client code, which stems from a URLClassLoader. 
>  The URLClassLoader is the loader of the current thread and Compiler, but 
> not @(clojure.lang.Compiler/LOADER).
>
> *Attempts:*
>
> I've tried wrapping the clojure-hadoop loading code with 
> .setContextClassLoader on some obvious candidates and binding 
> *use-context-classloader* around the code doing the loading, with no avail. 
>  I've tried changing the schema code to reference the class in different 
> ways (class (resolve 'long)), (class 'long), etc and that hasn't made a 
> difference.  I've checked and the clojure-hadoop jar doesn't contain any 
> .class files for clojure, schema, or other offending code.  
>
> *Plea:*
>
> I suspect there's something obvious I'm missing.  (In retrospect it seems 
> like the design of Schema may be suboptimal in light of this, but if 
> possible I'd like to figure out a workaround without changing that 
> substantially). Thanks in advance for your help -- any and all pointers are 
> welcome.  
>
> -Jason
>
>
>
>

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