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From Nicolas Lalevée <nicolas.lale...@hibnet.org>
Subject Re: Classloading issue
Date Mon, 12 May 2014 08:36:37 GMT

Le 12 mai 2014 à 02:51, Martin Gainty <mgainty@hotmail.com> a écrit :

>> Subject: Re: Classloading issue
>> From: nicolas.lalevee@hibnet.org
>> Date: Mon, 12 May 2014 01:51:12 +0200
>> To: dev@ant.apache.org
>> 
>> 
>> Le 12 mai 2014 à 01:34, Antoine Levy Lambert <antoine@gmx.de> a écrit :
>> 
>>> Hello Nicolas,
>>> 
>>> I have tried your test case and it is failing as you except :
>>> 
>>> BUILD FAILED
>>> /Users/antoine/dev/asf/ivyde-trunk/test/ssh-resolver/build.xml:27: java.lang.NoClassDefFoundError:
com/jcraft/jsch/agentproxy/AgentProxyException
> 
> MG>Hi Nicholas
> MG>local classloader cannot resolve jdsch-agentproxy.core-0.0.7.jar?
> MG>what happens when you place
> MG>http://www.grepcode.com/snapshot/repo1.maven.org/maven2/com.jcraft/jsch.agentproxy.core/0.0.7/jsch.agentproxy.core-0.0.7.jar
> MG>on SYSTEM classpath?

jsch-agentproxy isn't on the classpath on purpose. If we don't need the ssh agent feature,
we shouldn't need this jar.

Nicolas

> 
>>> 	at org.apache.ivy.plugins.repository.ssh.AbstractSshBasedRepository.getSession(AbstractSshBasedRepository.java:108)
>>> 	at org.apache.ivy.plugins.repository.ssh.SshRepository.resolveResource(SshRepository.java:82)
>>> 	at org.apache.ivy.plugins.repository.ssh.SshResource.resolve(SshResource.java:101)
>>> 
>>> The line 108 in AbstractSsshBasedRepository contains this :
>>> 
>>>      return SshCache.getInstance().getSession(host, port, user, userPassword,
getKeyFile(),
>>>          getKeyFilePassword(), getPassFile(), isAllowedAgentUse());
>>> 
>>> getSession is a method which calls attemptAgentUse.
>> 
>> It is only called is attemptAgentUse is true. In our case it is false.
>> 
>>> Does this explain why an attempt to load AgentProxyException happens at that
time ?
>> 
>> I have plugged a debugger, and the class loading exception is raised on the call
of SshCache.getInstance(). As far as I can tell, it is the class SshCache which fails to load,
but I don't understand why.
>> 
>> Nicolas
>> 
>>> 
>>> Regards,
>>> 
>>> Antoine
>>> 
>>> On May 11, 2014, at 5:41 PM, Nicolas Lalevée <nicolas.lalevee@hibnet.org>
wrote:
>>> 
>>>> Hi,
>>>> 
>>>> I need some help to understand a bug around classloading (nothing that particular
to Ivy).
>>>> 
>>>> I was looking into IVY-1471 [1] and I don't understand why it is failing
that way. In the classpath there are both Ivy and Jsch, but not the optional jar related to
managing the ssh agent via jsch. And it is failing because a class in that optional jar is
not found. But I don't understand why the classloader is looking for it in the first place.
>>>> 
>>>> The error is raised is AbstractSshBasedRepository, on the call of SshCache.getInstance()
[2]. But as far as I can tell, nothing in the loading of the SshCache [3] class requires AgentProxyException.
The class is only needed by the function SshCache#attemptAgentUse() [4], which will be called
at runtime, if the end user actually want ssh agent support, in which case it would naturally
fail. But here it fails very earlier.
>>>> 
>>>> I have made a test case you can test with its build.xml, no IvyDE required
there [5].
>>>> 
>>>> Am I missing something ? Is there a special treatment for the loading of
Exception classes ?
>>>> 
>>>> Nicolas
>>>> 
>>>> [1] https://issues.apache.org/jira/browse/IVY-1471
>>>> [2] https://fisheye6.atlassian.com/browse/ant/ivy/core/trunk/src/java/org/apache/ivy/plugins/repository/ssh/AbstractSshBasedRepository.java?hb=true#to108
>>>> [3] https://fisheye6.atlassian.com/browse/ant/ivy/core/trunk/src/java/org/apache/ivy/plugins/repository/ssh/SshCache.java?hb=true
>>>> [4] https://fisheye6.atlassian.com/browse/ant/ivy/core/trunk/src/java/org/apache/ivy/plugins/repository/ssh/SshCache.java?hb=true#to300
>>>> [5] http://svn.apache.org/repos/asf/ant/ivy/ivyde/trunk/test/ssh-resolver/
>>>> 
>>>> 
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>>> 
>>> 
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>> 
>> 
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> 		 	   		  


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