Server Suspend Mode allowing new requests with started session - graceful draining of sessions without a load balancer

[jjakub]

Is it possible to configure server suspend mode to allow new requests that already have session started on stopped node (sending jsessionId), but reject requests without session ?

It would like to emulate parallel deployment which is what I actually need.

How can I currently achieve graceful draining of sessions without a load balancer ?

WildFly 9 Final is released! · WildFly sta

Server Suspend Mode / Graceful Shutdown

Previously, in order to achieve graceful draining of sessions/requests, a load balancer was required. The new server suspend mode in WildFly, once activated rejects new requests but allows old ones to complete. Once the suspension process has completed the server can either be stopped without aborting in-flight transactions, left in suspended state while maintenance is performed, or returned back to running state where new requests are once again allowed.

PS 1

In Tomcat there is such functionality out of the box

Apache Tomcat 7 Configuration Reference (7.0.63) - The Context Container - parallel deployment

You may deploy multiple versions of a web application with the same context path at the same time. The rules used to match requests to a context version are as follows:

• If no session information is present in the request, use the latest version.
• If session information is present in the request, check the session manager of each version for a matching session and if one is found, use that version.
• If session information is present in the request but no matching session can be found, use the latest version.

The Host may be configured (via the undeployOldVersions) to remove old versions deployed in this way once they are no longer in use.

PS2

In eap 6 parallel deployment is not possible: parrallel / side by side deployment

[ctomc]

how do you shutdown / suspend the server?

to use new graceful shutdown you need to pass timeout parameter to :shutdown or :suspend operations, without it it wont do it grecefuly

[jjakub]

I haven't tested it yet, I want to know in theory, but assuming I pass timeout of 2 hours, will it allow new requests from client that already have session on this node ?

If yes, if it will allow new requests with session on this node, than this is what I need, but from description, I think it will not allow any new requests at all:

Previously, in order to achieve graceful draining of sessions/requests, a load balancer was required. The new server suspend mode in WildFly, once activated rejects new requests but allows old ones to complete.

but than there still is a problem of graceful draining of sessions not only previously, but also in WildFly9, so this advertising description would be misleading.

[ctomc]

if you are interested in theory then you should read design documents on this subject

Wildfly suspend and resume (aka graceful shutdown)

https://docs.jboss.org/author/display/WFLY9/Suspend,+Resume+and+Graceful+shutdown

[pferraro]

Server suspend does not work this way.  Suspending a server rejects *all* new requests and waits for requests that have already been received to complete.  There is no exception case for web requests for existing sessions.

At present, true session draining be achieved via mod_cluster, but this operates completely outside of the deployment/shutdown mechanism;