Replication Queue details
Until Infinispan 4.1.0.CR2, replication queue always flushed data with async marshalling turned on, which meant that there was a small gap where flush calls could be reordered. Since 4.1.0.CR3, async marshalling configuration is taken into account, and decides whether the flush calls goes directly to the JGroups layer, or whether an intermediate handing over to a different thread occurs. The advantages of using async marshalling with replication queue are less than clear because replication queue itself already makes client requests return faster, so it's generally recommended to have async marshalling turned off, or element's maxThreads set to 1, when replication queue is turned on.