1. An apparatus comprising: at least one processor; a memory coupled to the at least one processor; a streaming application residing in the memory and executed by the at least one processor, the streaming application comprising an operator graph that includes a plurality of data tuples; a performance monitor residing in the memory and executed by the at least one processor, the performance monitor monitoring resource usage of at least one computer system resource by each of the plurality of data tuples processed by the plurality of operators in the operator graph, wherein the resource usage for a selected data tuple comprises a usage of the at least one computer system resource during the processing of the selected data tuple by at least two of the plurality of operators that process the selected data tuple; and a tuple breakpoint mechanism residing in the memory and executed by the at least one processor, the tuple breakpoint mechanism including a tuple breakpoint that defines at least one criterion for usage of the at least one computer system resource by at least one data tuple, and when the tuple breakpoint mechanism determines the tuple breakpoint fires based on information from the performance monitor, the tuple breakpoint mechanism halts at least one operator in the operator graph and displays information regarding a data tuple that caused the tuple breakpoint to fire.