  We introduce a set of state access patterns suitable for managing state in
embarrassingly parallel computations on streams. The state access patterns are
useful to model typical stream parallel applications. We present a
classification of the patterns according to the extent and way in which the
state is modified. We define precisely the state access patterns and discuss
possible implementation schemas, performances and possibilities to manage
adaptivity (parallelism degree) in the patterns. We present experimental
results relative to an implementations on top of the structured parallel
programming framework FastFlow that demonstrate the feasibility and efficiency
of the proposed access patterns.
