Possible deadlock on framework startlevel change
------------------------------------------------
Key: FELIX-384
URL: https://issues.apache.org/jira/browse/FELIX-384
Project: Felix
Issue Type: Bug
Components: Declarative Services
Reporter: Felix Meschberger
Assignee: Felix Meschberger
Priority: Critical
Fix For: 1.0.0
Felix SCR uses java synchronization on component manager instances to prevent
synchronous execution of certain actions like activation and deactivation. In
concert with the locking implemented by the Felix framework, deadlocks may
occurr in certain situations.
For example: If the framework has been started but the SCR Activator queue
still has a deadlock and the framework is instructed to shutdown.
The start level service will now stop bundles in the FelixStartLevel thread. At
one point in time Bundle X will be stopped and the framework holds the bundle
lock while stopping the bundle. Stopping the bundle causes a synchronous
STOPPING event being handled by the SCR, which causes immediate deactivation of
all components of the bundle. This causes the
AbstractComponentManager.deactivateInternal method to be called which is
synchronized on the instance.
At the same time, the components of Bundle X may still be scheduled for
activation in the SCR Activator queue handled by the SCR Component Actor
thread. This thread may be activating a component of Bundle X trying to
register the component as a service in the
AbstractComponentManager.activateInternal method (synchronized on the
instance). Registering the service tries to acquire the bundle lock first.
The result is a deadlock between the FelixStartLevel thread (holding the bundle
lock and waiting for the component manager lock) and the SCR Component Actor
thread (holding the component lock and waiting for the bundle lock).
While this is probably a seldom situation, it must be prevent from happening
nevertheless.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
