Re: [jboss-as7-dev] Graceful Shutdown
The idea is that existing permit holders (which includes already-running
requests, already-open transactions, etc.) can still get new permits,
but those who do not already have a transaction running or open sessions
or whatever cannot and should be redirected to another node.
On 09/16/2011 09:12 AM, Scott Marlow wrote:
Is this a fail-fast design? Or should all currently running user
requests succeed? If new transactions cannot be started, I would think
that means some running user requests will fail.
On 09/13/2011 10:31 AM, David M. Lloyd wrote:
> We've worked out the rough outline of how graceful shutdown will work in
> AS7.
>
> The process of graceful shutdown actually is reflected by a number of
> states:
>
> 1. Running - all services acting normally
> 2. Suspending - services refuse new "permits" (see below), existing
> permits are allowed to be retained (and threads running under such a
> permit may still acquire new permits)
> 3. Suspended - no permits are present and none may be issued
> 4. Shutting Down - our existing server stop process
>
> The following transitions are allowed:
>
> 1. Running → Suspending: Transition occurs at user request (to suspend
> or gracefully shut down).
> 2. Suspending → Suspended: Transition occurs when all permits are
> cleared.
> 3. Suspending → Running: Transition occurs at user request (to exit
> suspend mode or cancel graceful shutdown before it completes).
> 4. Suspended → Running: Transition occurs at user request (to exit
> suspend mode).
> 5. Suspended → Shutting Down: Transition occurs automatically (if a
> graceful shutdown was requested) or at user request (if a shut down
> request of any kind is entered in the Suspended state).
> 6. Running → Shutting Down: Transition occurs at user request (to shut
> down the server "un-gracefully").
>
> These "permits" are issued by the "Shutdown Manager", whose job
is to
> manage these states. They are issued corresponding to the following
> events:
>
> 1. The invocation of an EJB method
> 2. The creation of a web session
> 3. A creation of a transaction
> 4. Probably some situations involving HQ and/or JCA
>
> When a permit cannot be issued due to the server shutting down, a
> standard exception message should be produced so that the user can see a
> familiar error message regardless of what mechanism is used to access
> the server.
>
--
- DML