Ability to disable automatic parent classloader delegation
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Key: FELIX-712
URL: https://issues.apache.org/jira/browse/FELIX-712
Project: Felix
Issue Type: Improvement
Components: Framework
Affects Versions: felix-1.2.0
Reporter: Don Brown
In debugging a strange issue why a certain test was passing in IDEA, but
failing in Maven, we discovered that under certain conditions, Felix will
delegate to the parent classloader if it detects another class in the stack
who's classloader differs from the classloader of Felix. Specifically, in
org.apache.felix.framework.searchpolicy.R4SearchPolicyCore starting in line
541, there is the problematic code block that has this comment:
// At this point, the class/resource could not be found by the bundle's
// static or dynamic imports, nor its own content. Before we throw
// an exception, we will try to determine if the instigator of the
// class/resource load was a class from a bundle or not. This is
necessary
// because the specification mandates that classes on the class path
// should be hidden (except for java.*), but it does allow for these
// classes/resources to be exposed by the system bundle as an export.
// However, in some situations classes on the class path make the faulty
// assumption that they can access everything on the class path from
// every other class loader that they come in contact with. This is
// not true if the class loader in question is from a bundle. Thus,
// this code tries to detect that situation. If the class
// instigating the load request was NOT from a bundle, then we will
// make the assumption that the caller actually wanted to use the
// parent class loader and we will delegate to it. If the class was
// from a bundle, then we will enforce strict class loading rules
// for the bundle and throw an exception.
What that means is if if you call Bundle.loadClass() from a non-bundle class
and you happen to have a class in your stack, which was loaded from a different
classloader than Felix, Felix will try to fix your problem by allowing parent
classloader delegation. This was the cause of the breakage for us because
Maven's Surefire plugin uses its own classloader to load several of its classes
and Felix found those in the call stack and decided to enable parent
delegation. In IDEA, all the classes were loaded by the same classloader, so
our tests passed.
Specifically, we have code that sits outside Felix and tries to load classes
from installed bundles. Felix sees that the call, by examining the stack, is
by code outside a bundle, so it enters this routine that may or may not,
depending on the execution environment, delegate the class loading to Felix's
class loader.
This ticket asks for a configuration setting to be able to disable this bit of
code.
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