Abstract: A system implements task contention reduction via policy-based selection. Tasks waiting to be performed are indexed in a task data structure that groups the tasks based on the resources to which the tasks pertain. Workers request batches of tasks for the workers to perform. A scan cycle includes building multiple batches of tasks by scanning the task data structure for a requesting worker. A policy (e.g., random or some other form of optimization) determines where the scan cycle starts in the data structure. Each batch of tasks is delivered to a worker along with a token that keeps the state of the scan cycle (e.g., where the scan cycle started, and where the next scan to build the next batch within the scan cycle begins). The worker returns the token with the next request for the next batch and the next batch is built based on the token's state information.

Abstract: A database management system provisions a database server that replicates assignments of resource identifiers to resources that are managed by another database server. Based at least in part on assignment of existing sets of identifiers to other database servers, the database management system identifies a set of identifiers that is distinct from these existing sets and assigns this set of identifiers to the provisioned database server. If the database management system detects an event that causes the database server to lose its ability to receive these assignments of identifiers from the other server, the database management system enables the database server to assign identifiers from its assigned set of identifiers.

Abstract: A system partitions a graph representation of relationships between block devices and associated snapshots into a plurality of cells to more evenly distribute computing resource usage attributable to the block devices and snapshots. The relationships may be analyzed to determine resource usage associated with the block devices and/or the snapshots wherein the resource usage corresponds to a mutation operation rate or number of mutation operations performed (or scheduled for performance). As a result of determining that the resource usage for a given cell exceeds a predetermined threshold for resource usage, the cell may be partitioned into a plurality of cells, and a portion of the corresponding block device(s), and subsequent snapshot(s) generated therefrom, may be assigned to the new cell.