The biggest weakness of Akka (Erlang for the JVM) is the GC. If you aren't really careful about memory usage it's easy to trigger big GC pauses that render you

The biggest weakness of Akka (Erlang for the JVM) is the GC. If you aren't really careful about memory usage it's easy to trigger big GC pauses that render your node unreachable by the rest of the cluster. CPU-intensive operations pose their own problems. EC2 doesn't have amazing context switching so sometimes Akka's internal dispatchers won't be able to get CPU time quickly enough to keep the cluster heartbeats going, also causing your node to be marked unreachable by the rest of the cluster. I imagine bare-metal would be far easier to work with in this regard. There are certainly ways to deal with these problems by tuning the GC and Akka failure detectors, but it's a serious problem with Akka.