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https://issues.apache.org/jira/browse/AMQ-4777?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13787659#comment-13787659
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Amichai Rothman commented on AMQ-4777:
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Update: I followed up on my original direction of investigation, and found out
that both dosgi and an app custom feature had included the osgi compendium
bundle as a dependency, and the latter even had osgi core specified in it.
Manually removing the three bundle references from the features xml files in
karaf/system folder before first launching Karaf seems to resolve the issue.
While there is now a usable workaround, there are still a few open questions
which hopefully someone can answer:
1. Should these bundles be referenced in the custom feature? It is created by
karaf-maven-plugin (3.0.0-SNAPSHOT) with includeTransitiveDependency set to
true for offline deployment. In the poms that define them as dependencies they
have scope set to 'provided'. Should such provided bundles be included in a
feature definition or not? Is this a bug? It's good for completeness and
documenting the real dependencies, but it also seems to break things here.
Perhaps features should support some form of 'provided' attribute for
dependencies?
2. Is Karaf supposed to do anything about such provided dependencies, or just
ignore them since they are already provided? Is this a bug?
3. How exactly do these bundle references cause ActiveMQ to fail?
4. Why does ActiveMQ fail silently and not show an error anywhere?
5. What can be improved in order to either protect against such occurrences (if
they are to be flagged as invalid) or make it clearer where the problem lies
for future instances of this error (this might happen with features other than
ActiveMQ)?
Any further insights would be appreciated :-)
> ActiveMQ broker silently fails to start in Karaf
> ------------------------------------------------
>
> Key: AMQ-4777
> URL: https://issues.apache.org/jira/browse/AMQ-4777
> Project: ActiveMQ
> Issue Type: Bug
> Components: OSGi/Karaf
> Affects Versions: 5.8.0
> Environment: Kubuntu 64-bit, Oracle JDK 7u40, Karaf 2.3.3
> Reporter: Amichai Rothman
> Assignee: Jean-Baptiste Onofré
>
> I have an application, deployed into Karaf. I install the activemq-broker
> feature, and one of the app bundles uses ActiveMQConnectionFactory to get a
> javax.jms.Connection instance and then uses the JMS API only (no other
> ActiveMQ-specific APIs in use). I'll note that this bundle depends on another
> bundle which uses the JMS API as well (no ActiveMQ imports there at all). The
> application also depends on other karaf features such as cxf-dosgi.
> ActiveMQ fails to start in a couple of ways, depending on the order of
> installation of the features and app:
> At first I got a LinkageError:
> java.lang.LinkageError: loader constraint violation: when resolving method
> "org.apache.activemq.ActiveMQConnectionFactory.createConne
> ction()Ljavax/jms/Connection;" the class loader (instance of
> org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) of the current
> class, com/myprojectgroup/bus/activemq/ActiveMQSession, and the class loader
> (instance of org/eclipse/osgi/internal/baseadaptor/D
> efaultClassLoader) for resolved class,
> org/apache/activemq/ActiveMQConnectionFactory, have different Class objects
> for the type Ljava
> x/jms/Connection; used in the signature
> at
> com.myprojectgroup.bus.activemq.ActiveMQSession.createConnection(ActiveMQSession.java:38)
> at
> com.myprojectgroup.messaging.jms.Session.open(Session.java:70)[68:com.myprojectgroup.messaging:0.1.0.SNAPSHOT]
> at
> com.myprojectgroup.messaging.jms.Session$1.run(Session.java:108)[68:com.myprojectgroup.messaging:0.1.0.SNAPSHOT]
> The only bundle that exports the javax.jms package is
> org.apache.geronimo.specs.geronimo-jms_1.1_spec, though after further
> investigation I found that the activemq-web-console bundle does have another
> copy of it internally, which I think might be the cause of the conflict (it
> does not import the package in the manifest, so I can't just remove the
> package from the jar since it won't find the package exported by the
> geronimo-jms bundle without a corresponding import declaration). The
> activemq-osgi bundle has a DynamicImport-Package: *, which may further
> complicate things. If it also had an explicit Import-Package directive for
> the statically-linked classes it uses such as javax.jms ones, perhaps it
> would go through the regular bundle classloading mechanism and avoid the
> problem - I think it takes precedence over dynamic imports, though I'm not
> sure).
> Next, I played around with reordering the installation, and got to another
> failure mode where there is no exception at all or any error in the logs, but
> the broker simply fails to start silently. Perhaps this is also caused by
> classloader issues but they are just occurring somewhere within ActiveMQ and
> being silently ignored. This mode of failure I've managed to recreate easily:
> On a fresh stock installation of Karaf 2.3.3, add two feature urls:
> features:addurl mvn:org.apache.activemq/activemq-karaf/5.8.0/xml/features
> mvn:org.apache.cxf.dosgi/cxf-dosgi/1.6-SNAPSHOT/xml/features
> (you might need to add the apache snapshot repo to karaf for it to find the
> dosgi snapshot feature)
> And then install them in this order:
> features:install -v cxf-dosgi-discovery-distributed activemq-broker
> The broker will not be started, although the logs will have no errors.
> Strangely, if you now uninstall the activemq-web-console bundle (not feature)
> and restart karaf, the broker will start ok. Also if you install only
> activemq-broker and not dosgi, it will start ok.
> To simplify, I found that instead of the dosgi feature it's enough to install
> and start the mvn:org.osgi/org.osgi.compendium/4.3.1 bundle before installing
> activemq-broker to make it fail - this is from looking at the innards of the
> dosgi feature, however if I remove this bundle from the feature the broker
> still fails to start, so it's not the only bundle causing problems, but just
> an example.
> The only workaround I've found so far is to install everything, then
> uninstall the activemq-web-console bundle and restart - then everything works
> as it should. Strangely, not installing it in the first place doesn't work
> either - the broker won't start unless the web console is first started, then
> uninstalled.
> Some details of the LinkageError are in http://pastebin.com/TKZt7hUA (pasted
> to karaf irc channel originally).
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