A mechanism for varying stress on a software application while processing real user workloads is disclosed. A method of embodiments of the invention includes configuring application resources for a recovery configuration whose service levels are satisfactory. The application resources are associated with the software application. The method further includes configuring the application resources for stress configurations to affect service levels, and transitioning the application resources from the recovery configuration to a stress configuration for a time duration, while the application resources of the stress configuration are transitioned back to the recovery configuration. The method further includes determining a next stress configuration and a time duration combination to vary stress such that user service levels are unobtrusively affected by limiting the time duration in inverse relation to an uncertainty in predicting the service level impact of the stress configuration.