Hierarchical Locks for Transactional Memory Concurrency

The single global lock is segmented into multiple hierarchical locks organized in a tree structure. Each node in the lock hierarchy represents a shared resource, with root locks representing broader resource groups and leaf locks representing specific resources. This segmentation allows threads to acquire only the locks necessary for their specific resource access patterns, enabling concurrent execution of transactions that access different resources while maintaining serialization for transactions accessing the same resource hierarchy.

The lock mechanism transitions from a single-dimensional global lock to a multi-dimensional hierarchical structure organized as a tree. Each dimension in the hierarchy represents a level of resource abstraction, with threads navigating through multiple dimensions to acquire appropriate locks. This dimensional transformation enables fine-grained control over serialization scope while maintaining a systematic and manageable structure through the tree organization of locks and their associated resource hierarchies.

The shared hardware resources for conflict detection and store buffering are logically segmented by introducing hierarchical locks that partition the transaction execution space. Each lock level creates a isolation boundary that effectively divides the shared hardware resources into smaller contention domains. This segmentation reduces the probability of capacity-overflow aborts by limiting the number of concurrent transactions competing for the same hardware resources at any given time, while still allowing high utilization through parallel execution in different lock partitions.