04122: | Provided services not removed on a graceful shutdown |
Category: Component
Status: ClosedSeverity: HIGH
Reported against release: 0.8
Fixed in release: 0.9
PROBLEM:When components are shut down via the shell "process -stop" command,
their services do not always go away. Components using the services do
not receive a "providedServiceRemoved()" callback. ANALYSIS:The de-registration of services from the Jini Lookup Service by the
Jini Discovery Plugin is performed via a thread registered as a
shutdown hook (see java.lang.Runtime.addShutdownHook()). The nature of
shutdown hooks is that they only have a limited amount of time to run,
and no guarantee of being able to complete. After some testing, it is
also apparent that shutdown hooks are executed in parallel with each
other and with the rest of JVM shutdown, which includes disabling of
socket access.
This defect was originally created because of a component whose
application code registered an additional shutdown hook, in addition to
the Component Services shutdown hook. In these circumstances, there
just wasn't enough CPU cycles to go around to get the services de-
registered in time.
The use of the shutdown hook to de-register services in the Jini
Discovery plugin was always intended as a convenience, not as a
guarantee. Service de-registration was always the first action
performed by the shutdown hook, therefore there is really no fix to be
made. See the workaround section for discussion of what can be done to
avoid this problem. WORKAROUND:Note that using the shell "process -stop" command does not necessarily
connote a graceful shutdown of processes controlled by a container
manager.
For standalone process, the process is killed via the
java.lang.Process.destroy() method. Graceful shutdown of standalone
processes is an upcoming feature of Container Services.
For processes running in containers, they can use the ContainerAccess
API to register a callback with the container core. This callback
method will be used for a graceful shutdown.
|
