[Serverless] Ensure that only one subscription instance is active
维护者通常 7 天内回复
还没有人认领这个 Issue。
评估
- 难度
- 5/5
- 预计耗时
- 一周以上
- 新手友好度
- 20/100
- Issue 类型
- 功能
- 描述清晰度
- 基本清楚
- 活跃度
- 停滞
- 技术栈
- csharp
调研方向
Start by reading issue #161 for the proposed subscription position API, then trace how subscriptions are started and how their checkpoints are managed. The issue proposes an HTTP presence API and ongoing instance election, but leaves race conditions and the election design unresolved; done would require a decided approach that keeps one instance active and hands over activity when it shuts down.
由索引模型根据 Issue 内容生成。
描述
When a subscription is deployed as a serverless function or container, it's hard to control how many instances are currently active. It will inevitably lead to multiple instances running simultaneously, processing the same events (which could be a problem) and overriding the checkpoint (another potential problem).
#161 suggests adding an HTTP API to subscriptions to report their positions. Another API could also expose the subscription presence with some unique id. The id could be generated on startup and remains static for a given running instance.
It would allow creating a self-managed distributed control plane for subscription services. It could work like this:
- A newly instantiated service makes several calls to its own HTTP endpoint, assuming the endpoint is load balanced with a round-robin strategy
- It will collect all the responses from running instances and can understand how many are there
- If there's only one instance, the subscription will mark itself as active. This status is included in the API response.
- If there are multiple instances, and one of them is active, the subscription doesn't start
- If there are multiple instances, and none of them is active, the subscription decides to become active after gossiping with other instances
- When a subscription receives a gossip call from some instance that wants to activate, it will ensure that it is not active. Otherwise, the request should be denied.
This process needs to run continuously, so when one active subscription gets shut down, some other instance will become active.
I foresee some race conditions during the elections, but I am not sure yet if it's relevant.
- 主要语言
- C#
- 星标
- 512
- 派生
- 99
- 平均合并
- 5 天 6 小时
- 30 天内合并 PR
- 5
环境准备
- 提供 Dockerfile 或 Docker Compose 文件
- 没有 Pull Request 模板
- 阅读贡献指南
从这里开始
- 先读完整个 Issue，再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库，在一个分支上完成修改。
- 提交 Pull Request，并在描述里引用这个 Issue 编号。
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