This is indeed IMHO a central question in this topic, since parallelizing an algorithm is not an easy task. So I guess you still end up writing your algorithm

This is indeed IMHO a central question in this topic, since parallelizing an algorithm is not an easy task. So I guess you still end up writing your algorithm in OpenCL / Cuda and maybe use the serialization provided by this lib. Update: (Just read the hpcc_rootbeer.pdf slides.) You write your _parralellized_ implementation of an Algorithm in Java - and it will be executed on the GPU.