---
title: "Reactive Streams Demand-Driven Stream Processor | Distributed Systems Architecture Canon"
description: "Pull-based reactive stream processing architecture implementing the Reactive Streams standard to propagate dynamic demand signals and prevent memory buffer exhaustion."
image: "https://tinycto.tv/assets/distributed-systems/distributed_systems_architectures_og.jpg"
canonicalUrl: "https://tinycto.tv/distributed-systems/architectures/reactive-backpressure-flow-controller"
locale: "en"
---

# Reactive Streams Demand-Driven Stream Processor (`arch-reactive-backpressure-flow-controller`)

> **Architectural Pillar**: FLOW_BACKPRESSURE | **Archetype**: REACTIVE_FLOW_CONTROL
> **PACELC**: PA/EL | **Consensus Protocol**: None

Pull-based reactive stream processing architecture implementing the Reactive Streams standard to propagate dynamic demand signals and prevent memory buffer exhaustion.

### 3 Maturity Target Configurations

#### 1. Initial Target: 8,000 events/sec

- **Guarantees**: In-Memory Reactive Streams (Project Reactor / RxJava)
- **Infrastructure Topology**: Single-service microservice event pipeline with pull backpressure.
- **Operational Trade-Off**: Limited to a single JVM/process boundary.

#### 2. Scaled Target: 85,000 events/sec

- **Guarantees**: Distributed Network-Level Backpressure with RSocket / gRPC Flow Control
- **Infrastructure Topology**: Microservice mesh communicating over RSocket / HTTP/2 multiplexed streams with window-based byte flow control.
- **Operational Trade-Off**: Requires adoption of reactive programming libraries across all client engineering teams.

#### 3. Ultra-Scale Target: 1,200,000 events/sec

- **Guarantees**: Stateful Distributed Stream Backpressure with Apache Flink Credit Mechanism
- **Infrastructure Topology**: Flink cluster where TaskManagers exchange credit tokens before transmitting serialization buffers over the network.
- **Operational Trade-Off**: Requires strict checkpointing SLA management and cluster slot balancing.

### Handled Failure Modes

- `DS-FAIL-11: Unbounded In-Flight Queue Exhaustion`
- `DS-FAIL-03: Consumer Lag Spiral`


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