事件驱动死信队列架构

Architecture

死信队列架构图，展示重试策略、指数退避、最大重试阈值、失败消息的 DLQ 路由、运维告警和手动重处理工作流。该模板模拟异步消息系统的关键错误处理模式，确保处理失败时不会静默丢失任何消息。对于构建具有适当故障恢复机制的可靠事件驱动系统至关重要。

下载 .fz 文件

完整 FlowZap 代码

Producer { # Message Producer
n1: circle label:"Publish Message"
n2: rectangle label:"Serialize Payload"
n3: rectangle label:"Send to Main Queue"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left) [label="Enqueue"]
n3.handle(bottom) -> MainQueue.n4.handle(top) [label="Deliver"]
}
MainQueue { # Main Processing Queue
n4: rectangle label:"Receive Message"
n5: rectangle label:"Attempt Processing"
n6: diamond label:"Processing Succeeded?"
n7: rectangle label:"Acknowledge Message"
n8: rectangle label:"Increment Retry Count"
n9: diamond label:"Max Retries Exceeded?"
n4.handle(right) -> n5.handle(left)
n5.handle(right) -> n6.handle(left)
n6.handle(right) -> n7.handle(left) [label="Yes"]
n6.handle(bottom) -> n8.handle(top) [label="No"]
n8.handle(right) -> n9.handle(left)
n9.handle(top) -> n5.handle(bottom) [label="Retry"]
n9.handle(bottom) -> DLQ.n10.handle(top) [label="Exceeded"]
}
DLQ { # Dead Letter Queue
n10: rectangle label:"Route to DLQ"
n11: rectangle label:"Store Failed Message"
n12: rectangle label:"Alert Operations Team"
n13: rectangle label:"Manual Review Dashboard"
n14: diamond label:"Reprocessable?"
n15: rectangle label:"Requeue to Main"
n16: rectangle label:"Archive and Close"
n10.handle(right) -> n11.handle(left) [label="Preserve Context"]
n11.handle(right) -> n12.handle(left) [label="PagerDuty"]
n12.handle(right) -> n13.handle(left)
n13.handle(right) -> n14.handle(left) [label="Investigate"]
n14.handle(right) -> n15.handle(left) [label="Yes"]
n14.handle(bottom) -> n16.handle(top) [label="No"]
n15.handle(top) -> MainQueue.n4.handle(bottom) [label="Replay"]
}

为什么需要这个工作流？

Without proper error handling, failed messages in event-driven systems are silently lost or cause infinite retry loops that waste resources. A dead letter queue captures messages that exceed retry thresholds, preserving them for investigation and manual reprocessing while keeping the main processing pipeline healthy.

工作原理

Step 1: A message is received from the main queue and processing is attempted.
Step 2: If processing fails, the retry count is incremented and the message is requeued.
Step 3: Exponential backoff delays prevent overwhelming the failing service.
Step 4: After exceeding the maximum retry threshold, the message is routed to the DLQ.
Step 5: Operations teams are alerted via PagerDuty and can investigate through a dashboard.
Step 6: Reprocessable messages are requeued to the main queue after the root cause is fixed.

替代方案

Ignoring failed messages leads to data loss. Infinite retries waste resources and mask bugs. Logging failures without a DLQ makes recovery difficult. This template shows the complete failure handling lifecycle.

Key Facts

Template Name	事件驱动死信队列架构
Category	Architecture
Steps	6 workflow steps
Format	FlowZap Code (.fz file)