Fast Paxos Recovery via Leader Proposal
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Solution Overview
Problem
Distributed computing systems face challenges in maintaining synchronization and resolving conflicts efficiently, particularly in consensus algorithms like Paxos, which can introduce significant message delays and hinder system performance.
Innovation Solution
A modified fast Paxos algorithm that resorts to a Paxos algorithm with a known safe proposal, allowing a leader device to propose without performing the first phase, or determines which function a leader would propose using an immediately subsequent proposal number, and employs a predetermined mechanism to select conflicting requests, thereby reducing message delays and facilitating conflict resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standard Paxos algorithm is used to ensure consensus in distributed computing systems, then system reliability and synchronization are improved, but message delays increase and system performance deteriorates
Solution Approach 1:
The patent segments the Paxos algorithm into two distinct phases: the Prepare phase (steps 1-3) and the Accept phase (steps 4-6). This segmentation allows the system to perform different operations in different phases, enabling fast recovery by skipping the Prepare phase when the leader already knows a safe proposal number, thus reducing message delays while maintaining consensus reliability
Solution Approach 2:
The patent implements preliminary action by having the leader device pre-determine a safe proposal number before conflict resolution is needed. When a conflict occurs, the leader can immediately propose the pre-determined safe proposal without going through the full Paxos algorithm, thereby achieving fast recovery and reducing message delays while ensuring consensus
2Productivity
If the Fast Paxos algorithm is used to reduce message delays, then system performance is improved, but the ability to handle conflicting requests deteriorates
Solution Approach 1:
The patent implements a dynamic algorithm that can switch between Fast Paxos and standard Paxos based on the situation. When no conflict exists, the system operates in Fast Paxos mode for high throughput. When a conflict is detected, it dynamically transitions to standard Paxos mode to properly resolve the conflict, thus adapting to different conditions and maintaining both performance and conflict resolution capability
Solution Approach 2:
The patent changes the parameter of proposal number selection dynamically. In normal operation, proposal numbers are selected to enable fast processing. When conflicts are detected, the system changes to using predetermined safe proposal numbers determined through the Prepare phase, allowing the system to adapt its behavior based on the presence or absence of conflicts
3Reliability
If a leader device performs the complete Paxos algorithm to resolve conflicts, then consensus reliability is improved, but the number of message delays increases
Solution Approach 1:
The leader device performs preliminary action by determining a safe proposal number in advance (before conflict resolution is needed). When a conflict occurs, the leader can immediately use this pre-determined safe proposal number in the Accept phase without needing to execute the Prepare phase, thus achieving fast recovery that maintains consensus reliability while reducing message delays
Solution Approach 2:
The patent extracts the essential element needed for conflict resolution (the safe proposal number) and determines it in advance. This allows the system to take out the time-consuming Prepare phase from the conflict resolution process, keeping only the necessary Accept phase, thereby reducing recovery time while maintaining consensus correctness
Data Source
AI summary
A distributed computing system can achieve consensus while introducing fewer message delays by using an algorithm that allows the constituent devices to vote on functions received directly from one or more clients. If a conflict occurs, a leader device from among the devices can be selected such that the leader device already knows of the other devices' previous votes, and can determine an appropriate function to propose, using an immediately subsequent proposal number, without performing the first phase of the Paxos algorithm. Alternatively, each device can independently determine, by using the same repeatable mechanism used by a leader device, what function the leader device would propose, and can then vote for that function using the immediately subsequent proposal number. If the devices' votes again result in a conflict, the Paxos algorithm can be used, or additional iterations can be performed prior to resorting to the Paxos algorithm.