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Bug
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Resolution: Not A Defect
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Major
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None
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Jenkins 1.532, 1.549
Copy Artifact 1.28
Steps to produce the problem:
- Install Copy Artifact
- Disable Maven plugin
- Restart Jenkins
- Fails to load Copy Artifact with: (full stacktrace is attached)
1) Error injecting constructor, java.lang.NoClassDefFoundError: hudson/maven/MavenBuild at hudson.plugins.copyartifact.CopyArtifact$DescriptorImpl.<init>(Unknown Source)
I found followings:
- This can be reproduced when I package Copy Artifact with jdk 1.6.
- This cannot be reproduced when I package Copy Artifact with jdk 1.7.
It seems that something strange happens in Jenkins plugin loading system.
It may be a problem with guice 4.0 introduced in aea10298 (may be guice does not work with Java1.6).
What I will do are:
- Create a minimum plugin to reproduce the problem.
- Test what happens if reverted aea10298.
- Test what happens if downgrade guice to guice 3.0 (fails to compile?)
- is related to
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- Closed
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[JENKINS-21664] Plugins with optional dependencies and compiled with Java6 cause Exception in loading
ikedam
added a comment - Hmm... that difference seems caused by a6926e1c51c0650a48dec68cbe402248742dd55c.
Installed, but disabled plugins are registered to class loaders in Jenkins < 1.524.
ikedam
added a comment - Hmm... that difference seems caused by a6926e1c51c0650a48dec68cbe402248742dd55c .
Installed, but disabled plugins are registered to class loaders in Jenkins < 1.524. ikedam
added a comment - This problem seems caused for Class#getMethod("getDescriptor") in Descriptor#<init> tries to load classes in optional depended plugins.
It must be a problem with JDK.
I'm not sure why but I cannot reproduce this behavior without Jenkins.
ikedam
added a comment - This problem seems caused for Class#getMethod("getDescriptor") in Descriptor#<init> tries to load classes in optional depended plugins.
It must be a problem with JDK.
I'm not sure why but I cannot reproduce this behavior without Jenkins. ikedam
added a comment - I finally found the root cause.
Upcasting in codes cause class loading:
public void doSomething() { if(Jenkins.getInstance().getPlugin("dependee")) { Derived d = somemethod(); Base b = (Derive)d; // <- This causes load Derive even not executing doSomething(). } }
and in Java6,
for(Base b: getDerivedList())
{
someMethodForBase(b);
}
This code is compiled as following:
for(Derived b: getDerivedList()) // <- Base is changed to Derived { someMethodForBase(b); // Here causes upcasting. }
There are some exceptions:
- Upcasting to Object does not cause class loading.
- Conversion between generic types does not cause class loading. (as generic types are completely ignored in execution time)
- Base b = derivedList.get( i ); does not cause class loading.
- Base b = derivedIterator.next(); does not cause class loading.
ikedam
added a comment - I finally found the root cause.
Upcasting in codes cause class loading:
public void doSomething()
{
if (Jenkins.getInstance().getPlugin( "dependee" ))
{
Derived d = somemethod();
Base b = (Derive)d; // <- This causes load Derive even not executing doSomething().
}
}
and in Java6,
for (Base b: getDerivedList())
{
someMethodForBase(b);
}
This code is compiled as following:
for (Derived b: getDerivedList()) // <- Base is changed to Derived
{
someMethodForBase(b); // Here causes upcasting.
}
There are some exceptions:
Upcasting to Object does not cause class loading.
Conversion between generic types does not cause class loading. (as generic types are completely ignored in execution time)
Base b = derivedList.get( i ); does not cause class loading.
Base b = derivedIterator.next(); does not cause class loading.
ikedam
added a comment - This is not a issue with Jenkins, but Java language feature.
I wrote a tips note for this problem:
https://wiki.jenkins-ci.org/display/JENKINS/Tips+for+optional+dependencies
ikedam
added a comment - This is not a issue with Jenkins, but Java language feature.
I wrote a tips note for this problem:
https://wiki.jenkins-ci.org/display/JENKINS/Tips+for+optional+dependencies 
when depending on maven-plugin...
when depending on an original plugin...
It seems nothing to do with guice...