I wondered about that too, but the author points out that the VMs can re-converge: if you have one that does 5 times round a loop and another that does 10, they end up resynchronised.
Any kind of software with a message or input processing loop will naturally re-converge at the top of the loop. It's quite neat.
...but during that one iteration of the loop, the paths will diverge wildly.
In a typical message handling loop, the big-switch will immediately jump off to separate message-handling code, immediately wiping out the possibility of parallelisation.
Any kind of software with a message or input processing loop will naturally re-converge at the top of the loop. It's quite neat.