1. A computer implemented method for processing a stream of tuples comprising: receiving a stream of tuples to be processed by a plurality of processing elements operating on one or more computer processors, each processing element having one or more stream operators, wherein one or more of the stream operators include code configured to output tuples to one or more other stream operators; receiving a first tuple at a first stream operator, the first stream operator being configured to perform one or more operations on the first tuple and to output a second tuple; determining, using a tuple creation policy for the first tuple, that the first stream operator is permitted to generate the second tuple, wherein the tuple creation policy includes a first tuple creation parameter, the first tuple creation parameter defining a maximum number of associated spawn tuples that the first stream operator is permitted to generate for the first tuple; generating, by the first stream operator and in response to determining that the first stream operator is permitted to generate the second tuple, the second tuple; determining, using the tuple creation policy for the first tuple, that the first stream operator is not permitted to generate a third tuple; and removing, by the first stream operator and in response to determining that the first stream operator is not permitted to generate the third tuple, the first tuple from memory without processing the first tuple to create the third tuple.