Concurrent Set Insertion Using Sentinel Nodes and Optimistic Validation
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Solution Overview
Problem
Concurrent data structures in computer systems face challenges in efficiently performing insertion, removal, and membership test operations while maintaining thread safety and optimizing traversals.
Innovation Solution
A method and system for implementing a concurrent set using sentinel and entry nodes, where threads traverse the set to identify insertion points, acquire locks, validate nodes, and perform operations like insertion and removal with optimistic traversals, ensuring thread safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional locking mechanisms are used to ensure thread safety in concurrent data structures, then data integrity is maintained, but traversal efficiency and operation speed deteriorate due to lock acquisition overhead
Solution Approach 1:
The patent applies preliminary action by having threads validate node integrity and check for modifications before acquiring locks. Threads perform optimistic validation during traversal, only acquiring locks when actual modification is needed. This reduces lock acquisition overhead while maintaining thread safety, as most traversals complete without locking.
Solution Approach 2:
The patent introduces version stamps and validation markers as intermediary mechanisms between optimistic traversal and actual locking. These intermediaries allow threads to detect conflicts without immediately acquiring locks, enabling efficient conflict-free traversals while ensuring data integrity when conflicts are detected.
2Productivity
If optimistic traversal is used to improve operation speed, then traversal efficiency increases, but data integrity may be compromised without proper validation mechanisms
Solution Approach 1:
The patent implements feedback mechanisms where threads continuously validate node version stamps during optimistic traversal. If a node's version stamp indicates modification since last read, the thread receives feedback to retry the operation with proper locking. This feedback loop maintains data integrity while allowing efficient optimistic traversal for unchanged data.
Solution Approach 2:
The patent performs preliminary validation of node integrity and version stamps before proceeding with operations. Threads check validation markers in advance, and only proceed with optimistic modifications if validation passes. This preliminary action ensures data integrity is maintained while enabling high-speed optimistic operations.
3Reliability
If locks are acquired for every node access to ensure thread safety, then data consistency is maintained, but operation complexity and overhead increase
Solution Approach 1:
The patent applies local quality by acquiring locks only for specific nodes that are being modified, rather than locking entire data structures or all accessed nodes. Threads validate and lock only the minimal necessary scope (individual nodes or small node sets), reducing operation complexity and lock overhead while maintaining data consistency for modified elements.
Solution Approach 2:
The patent performs preliminary validation to determine which nodes require locking before acquiring locks. Threads validate node versions and modification needs in advance, then acquire locks only for nodes that actually require modification. This preliminary action reduces unnecessary locking complexity while ensuring data consistency where needed.
Data Source
AI summary
A method for inserting an object into a concurrent set including obtaining a key associated with the object, traversing the concurrent set using a first thread containing the key, identifying a first insertion point while traversing the concurrent set, where the first insertion point is before a current node and after a predecessor node, obtaining a first lock for the predecessor node after identifying the first insertion point, validating the predecessor node and the current node after obtaining the lock, inserting a new node into the concurrent set after validating, where the new node is associated with the object, and releasing the first lock after inserting the new node.