The technology described herein allows processing nodes in a parallel processing environment to determine whether a data partition is being atomically processed. The processing nodes can maintain the atomic processing of data by checking for challenger nodes assigned to the same partition and checking whether the node is still the leader node for a partition at a given frequency and/or at key points during the data processing flow. When a processing node detects a challenger node, the node self-terminates. When a challenger node detects no other nodes assigned to its data partition, then it designates itself or confirms itself as the leader node and begins or continues processing data within the partition. A node can detect other nodes by checking a node log that each processing node updates upon completing a survey of its present status.