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From "metatech (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (FELIX-3067) Prevent Deadlock Situation in Felix.acquireGlobalLock
Date Thu, 03 Sep 2015 14:32:45 GMT

    [ https://issues.apache.org/jira/browse/FELIX-3067?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14312259#comment-14312259
] 

metatech edited comment on FELIX-3067 at 9/3/15 2:32 PM:
---------------------------------------------------------

On top of the 5 measures given in a previous comment : 
6. Add "com.sun.xml.bind.v2.runtime.reflect" in the "Import-Package" section of the MANIFEST.MF
for camel-core, camel-blueprint, and camel-spring.  This workaround solves the JAXB deadlock
when calling "com.sun.xml.bind.v2.runtime.reflect.opt.Injector", which retrieves the "Accessor"
class by loading the class explicitly from the parent classloader (I think JAXB behiavour
is not very OSGi-friendly).  This allows JAXB to find the "Accessor", without falling back
to search in the dynamic imports. 


was (Author: metatech):
On top of the 5 measures given in a previous comment : 
6. Add "org.xml.sax,com.sun.xml.bind.v2.runtime.reflect" in the "Import-Package" section of
the MANIFEST.MF for camel-core, camel-blueprint, and camel-spring.  This workaround solves
the JAXB deadlock when calling "com.sun.xml.bind.v2.runtime.reflect.opt.Injector", which retrieves
the "Accessor" class by loading the class explicitly from the parent classloader (I think
JAXB behiavour is not very OSGi-friendly).  This allows JAXB to find the "Accessor", without
falling back to search in the dynamic imports. 

> Prevent Deadlock Situation in Felix.acquireGlobalLock
> -----------------------------------------------------
>
>                 Key: FELIX-3067
>                 URL: https://issues.apache.org/jira/browse/FELIX-3067
>             Project: Felix
>          Issue Type: Improvement
>          Components: Framework
>    Affects Versions: framework-3.0.7, framework-3.0.8, framework-3.0.9, framework-3.2.0,
framework-3.2.1, fileinstall-3.1.10
>            Reporter: Felix Meschberger
>         Attachments: FELIX-3067-sling.patch, FELIX-3067.patch, felix_unblock_deadlock.patch,
felix_unblock_deadlock_2.patch, felix_unblock_deadlock_v2.patch, felix_unblock_deadlock_v4.patch,
threaddump-ise-deadlock.txt, threads_locked_by_camel_type_converter
>
>
> Every now and then we encounter deadlock situations which involve the Felix.acquireGlobalLock
method. In our use case we have the following aspects which contribute to this:
> (a) The Apache Felix Declarative Services implementation stops components (and thus causes
service unregistration) while the bundle lock is being held because this happens in a SynchronousBundleListener
while handling the STOPPING bundle event. We have to do this to ensure the bundle is not really
stopped yet to properly stop the bundle's components.
> (b) Implementing a special class loader which involves dynamically resolving packages
which in turn uses the global lock
> (c) Eclipse Gemini Blueprint implementation which operates asynchronously
> (d) synchronization in application classes
> Often times, I would assume that we can self-heal such complex deadlck situations, if
we let acquireGlobalLock time out. Looking at the calles of acquireGlobalLock there seems
to already be provision to handle this case since acquireGlobalLock returns true only if the
global lock has actually been acquired.
> This issue is kind of a companion to FELIX-3000 where deadlocks involve sending service
registration events while holding the bundle lock.



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