X10 is a modern language built from the ground up to handle future parallel
systems, from multicore machines to cluster configurations. We take a closer
look at a pair of synchronisation mechanisms: finish and clocks. The former
waits for the termination of parallel computations, the latter allow multiple
concurrent activities to wait for each other at certain points in time. In
order to better understand these concepts we study a type system for a stripped
down version of X10. The main result assures that well typed programs do not
run into the errors identified in the X10 language reference, namely the
ClockUseException. The study will open, we hope, doors to a more flexible
utilisation of clocks in the X10 language.Comment: In Proceedings PLACES 2010, arXiv:1110.385