System resource usage by a streaming application processing workloads can be monitored. Based on the monitoring, at least one performance metric for the streaming application in processing the workloads can be determined. Based on the at least one performance metric, whether hosting of the streaming application is, or is near to, violating at least one criteria specified by a service level agreement for the streaming application can be determined. If so, at least one additional instance of at least one parallelizable operator of the streaming application that is currently executing can be initialized. Responsive to initializing the at least one additional instance of at least one of the parallelizable operators, a portion of the workloads can be directed to the at least one additional instance of at least one of the parallelizable operators.