1. A computer-implemented method comprising: receiving, for each of a plurality of task instances that execute one or more computer-executable instructions to perform a task, a plurality of performance measures that each represent an execution performance of a property of the respective task instance for a particular time interval, wherein the plurality of task instances are executed in parallel on one or more computers; for each task instance: determining, for each performance measure of the respective task instance, whether the respective performance measure exceeds a threshold value that is based on a function of a mean and a standard deviation of the performance measure that represent the same property as the respective performance measure; determining, for each of the performance measures that exceeds the threshold value, a score using the respective performance measure and a mean and a standard deviation of the performance measures that represent the same property as the respective performance measure; and combining the scores for the performance measure that represent the execution performance measure of the same property of the respective task instance to obtain a combined score value; ranking the combined score values associated with at least a subset of the plurality of task instances to identify an outlier; and terminating an execution of a particular task instance on a first computer and executing the particular task instance on a second computer different from the first computer based on the ranking of the combined score values, the particular task instance from the plurality of task instances.