presto-main/src/main/java/io/prestosql/execution/NodeTaskMap.java/NodeTaskMap/createPartitionedSplitCountTracker
class NodeTaskMap:        public PartitionedSplitCountTracker createPartitionedSplitCountTracker(TaskId taskId)
        {
            requireNonNull(taskId, "taskId is null");

            TaskPartitionedSplitCountTracker tracker = new TaskPartitionedSplitCountTracker(taskId);
            PartitionedSplitCountTracker partitionedSplitCountTracker = new PartitionedSplitCountTracker(tracker::setPartitionedSplitCount);

            // when partitionedSplitCountTracker is garbage collected, run the cleanup method on the tracker
            // Note: tracker can not have a reference to partitionedSplitCountTracker
            finalizerService.addFinalizer(partitionedSplitCountTracker, tracker::cleanup);

            return partitionedSplitCountTracker;
        }