I choose my words poorly.
Just reread and rethought.
That makes VoltDB rather sensitive to network digestion or partitioning I guess. How do you overcome this?
If a message doesn't come, nothing breaks; it just waits for another message. Usually this empty work is important when the workload is too light, hence the need to artificially push it along.
In the case where the pipe to an execution site is congested AND a foreign node's initiator hasn't sent any work to it in 5ms, then it's possible the empty work will be delayed several milliseconds and the clogged site will run slightly slower. There was some new code in the 0.9.01 release that made this empty work sending process much more reliable as well. In the end, it's not something I worry about a lot.
Network partitions are a problem in VoltDB in general, but not more so because of any of this. For now we expect you to run nodes on a single switch for this reason. One thing we're talking aboout is to not allow clusters with <= n/2 nodes to do work (optionally). This would prevent a cluster from ever splitting into two, still working clusters. We also expect to support redundant switches/networks in a future version (optionally).