Abstract: A mechanism and system are described for either releasing held resources in the case of a deadlock or to postpone requests for resources when a potential deadlock is detected. One technique involves a three pass algorithm for selecting a candidate, where the candidate is either a possessory entity or resource is used. The three passes are as follows: (1) determining the subset of candidates, which have the CAN-BE-VICTIM flag set on; (2) If pass one results in a subset with more than one candidates in it, process that subset to determine a second subset of candidates based on resource priority associated with a resource type; (3) If the second pass results in a subset with more than one candidate in it, process that subset to select the candidate that has been running or held the shortest length of time.

Abstract: Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Abstract: Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Abstract: According to a transaction-based locking approach, a request for a first lock on a particular resource is received from a first process, wherein the first process is associated with a first transaction. A first lock on the particular resource is granted to the first process. A request for a second lock on the particular resource is received from a second process. A determination is made whether the second process is associated with the first transaction. If the second process is associated with the first transaction, then a second lock on the particular resource is granted to the second process prior to the first lock being released.

Abstract: A method and apparatus for managing access to a resource using anticipatory lock conversions in a distributed lock management system is provided. According to the method, when an entity requests a lock on a resource, the entity is granted, if possible, a lock with a more restrictive lock mode than is required if it is determined that the entity may require the more restrictive lock mode in the near future.

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: Methods and systems are provided for providing locking in a system. The resource objects of the system can be persistent, and thus provide finer granularity locking by allowing shared resource objects to be dynamically allocated and de-allocated. The persistent nature of the resource objects allows for the dynamic allocation and de-allocation of the resource objects, while guarding against the abnormal release of resource locks that result in the possibility of inconsistent data. If abnormal release occurs, the affected resource object(s) are marked to indicate that they are in a "dubious" state. The dubious resource objects are not dynamically de-allocated, but are instead allowed to persist until corrective or validation actions are taken. If the locks are validly released, then the resource objects can be safely de-allocated.