Abstract: Order allocation techniques that reduce the number of stops that a container makes in the process of fulfilling a customer order is disclosed. In one embodiment, this is accomplished by first identifying a pod that stocks the largest number of different items in a customer order. Then, a second pod is identified that stocks the largest number of remaining items in the customer order. Ultimately, all items in the customer order are assigned a pod. The collection of pods defines a container path through the distribution center.

Abstract: A method and apparatus for managing access to resources is provided. When a process requires access to a resource, the process requests a lock on the resource from a lock manager unit that resides on the same node as the process. If a resource object for the resource does not exists, one is created in the lock manager unit, but not on lock manager units on other nodes. Because each lock manager unit does not have to store all resource objects, and resource objects are only created for resources that are actually used, the overhead of the lock management system is significantly reduced. Resources are grouped in recovery domains. When a lock manager unit that supported a recovery domain fails, the recovery domain is marked invalid. All resources in the recovery domain are considered invalid unless it would have been impossible for a failed instance to have held an exclusive lock on the resource. A snapshot of lock information is made before cleanup is performed on invalid resources.

Abstract: A method and apparatus are provided for managing resources in a system that has multiple nodes. Each resource of a plurality of resources is assigned to a lock club of a plurality of lock clubs. A master node is assigned to each lock club of the plurality of lock clubs. All resources that belong to each given lock club are mastered at the master node assigned to the given lock club. Club-to-master mapping information that indicates the master node for each lock club of the plurality of lock clubs is maintained. Which of the multiple nodes is a master node for a particular resource is determined by inspecting the club-to-master mapping to determine the master node assigned to the lock club to which the particular resource belongs. The system may use directory nodes by storing the club-to-master mapping information for each lock club on a directory node that is selected for the lock club by applying a hash function to the name of the lock club.

Abstract: A method and apparatus manage shared resources in a multiprocessing computer system. A coordinator process identifies resources to be operated upon by a plurality of worker processes. The coordinator process acquires locks to lock the resources on behalf of the plurality of worker processes. The plurality of worker processes then operate on the resources locked by the coordinator process.

Abstract: A method and apparatus for managing access to resources is provided. When a process requires access to a resource, the process requests a lock on the resource from a lock manager unit that resides on the same node as the process. If a resource object for the resource does not exist, one is created in the lock manager unit, but not on lock manager units on other nodes. Because each lock manager unit does not have to store all resource objects, and resource objects are only created for resources that are actually used, the overhead of the lock management system is significantly reduced. Resources are grouped in recovery domains. When a lock manager unit that supported a recovery domain fails, the recovery domain is marked invalid. All resources in the recovery domain are considered invalid unless it would have been impossible for a failed instance to have held an exclusive lock on the resource. A snapshot of lock information is made before cleanup is performed on invalid resources.

Abstract: A method for managing termination of a process that holds a resource lock on behalf of another process is described. A first process acquires a first lock to a resource on behalf of a second process to exclude other processes from accessing the resource. The second process then acquires a wait lock to the resource. Later, when a third process acquires the first lock to the resource, the third process determines whether the first process terminated without releasing the lock. If the first process did terminate without releasing the lock, the third process attempts to acquire the wait lock. In attempting to acquire the wait lock, execution of the third process is suspended until the second process releases the wait lock. Consequently, acquisition of the wait lock by the third process prevents concurrent access to the resource by the third process and the second process.