Virtual Waiting Room Ticketing for Zero-Latency Fair Access
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Solution Overview
Problem
Existing virtual waiting room systems either introduce latency during normal demand, fail to ensure global fairness, or allow unbounded user spikes leading to website crashes during high demand, making them ineffective in maintaining website availability and performance.
Innovation Solution
A virtual waiting room system with a ticket master and proxies that operates in relaxed and pressure modes, pre-allocating tickets during low demand to minimize latency and enforce a bounded user entry rate during high demand, using a distributed architecture with periodic proxy updates to the ticket master.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a virtual waiting room is implemented to bound user entry rate during high demand, then website availability is maintained, but latency is introduced during normal demand
Solution Approach 1:
The system dynamically switches between two operational modes: relaxed mode during normal demand and pressure mode during high demand. In relaxed mode, the virtual waiting room is disabled allowing zero latency. In pressure mode, the waiting room activates to bound the user entry rate. This dynamic adaptation resolves the contradiction by applying the appropriate control mechanism only when necessary.
Solution Approach 2:
The system changes the operational parameter of the virtual waiting room based on demand conditions. When demand is normal, the entry rate parameter is set to unlimited (relaxed mode). When demand spikes, the entry rate parameter is bounded to a predefined maximum (pressure mode). This parameter change allows the system to maintain availability during spikes while avoiding latency during normal operation.
2Reliability
If a centralized ticket master is used to ensure global fairness, then fairness is maintained, but latency increases due to constant communication
Solution Approach 1:
The ticket master pre-calculates and provides the queue head position to proxies in advance, before users actually need to enter. This preliminary action allows proxies to make admission decisions locally without real-time communication with the ticket master, eliminating communication latency while maintaining global fairness through the pre-established queue ordering.
Solution Approach 2:
The system segments the centralized ticket master functionality into distributed proxies that operate autonomously. Each proxy maintains local state including the queue head position and can independently admit users based on pre-received instructions from the ticket master. This segmentation reduces communication overhead while preserving global fairness through coordinated state management.
3Stability of the object's composition
If rate limiting is enforced to prevent website crashes, then website stability is maintained, but user experience degrades due to waiting
Solution Approach 1:
The rate limiting mechanism is made dynamic by switching between relaxed mode (no waiting) and pressure mode (rate limited). During normal demand, users experience no degradation. During high demand spikes, rate limiting is applied to maintain stability. This dynamic approach ensures website stability only when necessary, preserving user experience during normal operation.
Data Source
AI summary
A method by one or more computing devices functioning as a ticket master for a website that has a virtual waiting room, wherein the ticket master is communicatively coupled to a plurality of proxies controlling access to the website. When the ticket master is in a relaxed mode (as opposed to a pressure mode), the method includes pre-allocating a number of tickets to the plurality of proxies for a first upcoming time period and setting a queue head for the first upcoming time period to a ticket number of a last ticket created, wherein the number of tickets that are pre-allocated for the first upcoming time period is greater than a target number of users allowed to enter the website during the first upcoming time period but less than a predefined maximum sudden spike number.