The issue is about scattered cache replication across cluster nodes;
WildFly is started in clustered mode using a scattered cache for replicating HTTP session data across cluster nodes; all 4 nodes in the cluster are initialized with the following cli script:

embed-server --server-config=standalone-ha.xml
/subsystem=jgroups/channel=ee:write-attribute(name=stack,value=tcp)
/subsystem=infinispan/cache-container=web/scattered-cache=testScattered:add()
/subsystem=infinispan/cache-container=web:write-attribute(name=default-cache, value=testScattered)

The test is run with wildfly-18.​0.0.Final.zip;
The same tests run with version wildfly-17.​0.1.Final.zip do not have any problem;
hence this looks like a regression;

As usual, we test that the serial value stored in the scattered cache is incremented at every call: when this is not true, we say we have a sampling error;

Using MOD_JK as load balancer, we have a 22.46% of sampling errors with wildfly-18.​0.0.Final.zip (0% with wildfly-17.​0.1.Final.zip):

• OK eap-7.x-clustering-http-session-shutdown-scattered with wildfly-17.​0.1.Final.zip
• ERROR eap-7.x-clustering-http-session-shutdown-scattered with wildfly-18.​0.0.Final.zip

Using HAPROXY as load balancer, we have a 1.71% of sampling errors with wildfly-18.​0.0.Final.zip (0% with wildfly-17.​0.1.Final.zip):

• OK eap-7.x-clustering-http-session-shutdown-scattered with wildfly-17.​0.1.Final.zip
• ERROR eap-7.x-clustering-http-session-shutdown-scattered with wildfly-18.​0.0.Final.zip

Using MOD_CLUSTER as load balancer, we have a 1.85% of sampling errors with wildfly-18.​0.0.Final.zip (0% with wildfly-17.​0.1.Final.zip):

• OK eap-7.x-clustering-http-session-shutdown-scattered with wildfly-17.​0.1.Final.zip
• ERROR eap-7.x-clustering-http-session-shutdown-scattered with wildfly-18.​0.0.Final.zip

On the server we deploy, as usual, clusterbench (see attachment clusterbench-ee8.ear).