Deadlock during delivery of resolved event
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Key: FELIX-2597
URL: https://issues.apache.org/jira/browse/FELIX-2597
Project: Felix
Issue Type: Improvement
Components: Framework
Affects Versions: framework-3.0.2
Reporter: Richard S. Hall
Assignee: Richard S. Hall
Priority: Minor
Fix For: framework-3.2.0
When the framework resolves a bundle, it fires the RESOLVED event to
synchronous bundle listeners while holding the global lock. This caused a
deadlock in a specific scenario where two threads T1 and T2 were racing to
resolve bundled B1 and B2, respectively. T1 was resolving a dynamic import for
B2 which started from a loadClassInternal() call from the JVM which locks B2's
class loader. T1 lost the race for the global lock and had to wait for T2 to do
its resolve of B2. T2 ended up firing a RESOLVED event to B1. In B1's callback
method, a loadClassInternal() was triggered by T2 when it accessed some static,
which caused it to deadlock when the JRE tried to lock the B1's class loader on
T2, which was already held by T1.
This issue is actually related to the JVM being too aggressively in its locking
of class loaders:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4670071
Regardless, we might be able to loosen this up a little bit by not holding the
global lock at all. This might slightly violate the definition of synchronous
bundle listener, since the state could change, but at least it will still be
delivered synchronously on the instigating thread.
More information here:
https://glassfish.dev.java.net/issues/show_bug.cgi?id=13329
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