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We propose a novel execution model for the implicitly parallel execution of data parallel programs in the presence of general I/O operations. This model is called hy-brid because it combines the advantages of the standard execution models fork/join and SPMD. Based on program analysis the hybrid model adapts itself to one or the other on the granularity of individual instructions. We outline compilation techniques that sys-tematically derive the organization of parallel code from data flow characteristics aiming at the reduction of execution mode switches in general and synchronization/communi-cation requirements in particular. Experiments based on a prototype implementation show the effectiveness of the hybrid execution model for reducing parallel overhead. 1