alibaba/Sentinel

sentinel-dashboard并发下流控规则丢失问题

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#1,346 opened on Mar 19, 2020

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 (11 comments) (0 reactions) (1 assignee)Java (23,109 stars) (8,150 forks)batch import
area/dashboardgood first issuekind/bug

Description

多人同时操作流控规则查询和添加时有概率出现规则丢失的情况。配置中心Apollo 1.apiQueryMachineRules查询操作分为几步 a.从配置中心Apollo获取规则 b.清空内存中appRules等信息 c.循环保存规则信息至内存appRules d.返回规则列表 2.apiAddFlowRule添加操作分为几步 e.保存app规则至内存appRules，若该app无配置，则新建 f.推送内存appRules等信息到配置中心Apollo

多人并发操作情况下，假如某app已存在规则_X_、Y，添加_Z_规则时，有人访问控制台查询规则列表，并至b处， 这时添加操作开始执行至 e 处读取无配置并新建往里面塞入_Z_。然后推送只有Z的列表到Apollo保存。 此时两个操作执行结束后，X、_Y_丢失。

Contributor guide

Tech stack
java
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
JavaConcurrencySentinel basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the race condition in Sentinel dashboard's `apiQueryMachineRules` and `apiAddFlowRule` methods. Look at the code that reads from Apollo and updates local cache. Consider adding synchronization or using concurrent data structures to prevent lost updates. Review existing comments for proposed solutions.