A method includes receiving a request to perform a shuffle operation on a data stream, the request including a set of initial key ranges: generating a shuffler configuration that assigns a shuffler from a set of shufflers to each of the initial key ranges; initiating the set of shufflers to perform the shuffle operation on the data stream; analyzing metadata statistics to determine whether a shuffler configuration update event occurs, the metadata statistics produced by the set of shufflers during the shuffle operation and indicating load statistics for each shuffler in the set of shufflers; and upon occurrence of the shuffler configuration update event and during the shuffle operation, altering the shuffler configuration based at least in part on the metadata statistics to produce an assignment of shufflers to key ranges that is different from the assignment of shufflers to the initial key ranges.