An operator locking tool allows a user to define a lock profile for one or more operators in a streaming application. The lock profile preferably specifies lock criteria and one or more corresponding lock actions that are taken when the lock criteria is satisfied. The lock criteria can include operator performance, resource utilization, events, and user-defined triggers. The lock actions can include blocking tuple entry, blocking tuple exit, halting tuple processing, processing high-priority tuples while not processing other tuples, allowing tuples to exit an operator only when specified exit criteria is satisfied, and enabling bypass of an operator. Locking can be done for individual operators or for a group of operators.