Enhanced barrier operator within a streaming environment

A computer program product for processing data, comprising:

• a computer-readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising:
• computer readable program code to establish an operator graph defining at least one execution path through operators of a plurality of processing elements executing on a plurality of compute nodes, wherein each of the operators is configured to perform a respective one or more operations on tuples of streaming data, and wherein a first processing element in the operator graph includes a barrier operator that joins the output of a plurality of upstream operators included in one or more of the plurality of processing elements;
• and
• computer readable program code to, upon determining at least one of (i) one or more timeout conditions have been satisfied at the barrier operator and (ii) a punctuation signal has been received at the barrier operator, before data has been received from all of the plurality of upstream operators, generate output data at the barrier operator without the data from at least one of the plurality of upstream operators, comprising computer readable program code to:
• determine an output pattern for each of the at least one upstream operators, based on historical data tuples received from the respective upstream operator and regardless of a data type of the historical data types;
• determine substitute data tuple output values for each of the at least one upstream operators, based on the respective output pattern and the historical data tuples received from the respective upstream operator;
• and
• join the substitute output values with received data tuple output values from other operators in the plurality of upstream operators to generate the output data.