DEV Community

Apache SeaTunnel
Apache SeaTunnel

Posted on

Building a Trillion-Scale Data Sync System: The Untold Story of Apache SeaTunnel

“How challenging is designing a system supporting trillion-level data synchronization? Let me tell you a from-scratch story…”

The Midnight SOS

One late night in 2021, just as I was about to shut down my computer, an urgent call came from operations:

“Help! The entire data sync system has crashed. Over 3,000 table synchronizations are backlogged, and business systems are triggering alarms…”

The voice on the line belonged to a business line tech lead, thick with anxiety. This wasn’t our first emergency, but the scale was unprecedented:

Key Metrics

  • Daily Data Volume: 100+ TB
  • Concurrent Sync Jobs: 3,000+ tables (batch & streaming)
  • Latency SLA: Seconds
  • Current State: 3+ hours behind, worsening

“System resource usage?”

“A nightmare! Database connections maxed out, CPU at 80%, memory alerts…”

An emergency patch deployed overnight provided temporary relief. Post-mortem analysis and community discussions revealed this wasn’t an isolated incident but an industry-wide pain point.

Why Existing Solutions Failed

┌───────────────────┐
│ 1. Waste of resources │──► Tasks occupy too much memory and CPU, and occupy too many database connections
├──────────────────┤
│ 2. Poor performance & scalability │──► Performance cannot keep up, and adding new data sources requires changing a lot of code
├─────────────────┤
│ 3. Poor stability │──► Synchronization crashes occur several times a year, and often when others are celebrating a holiday, we are recovering
├─────────────────┤
│ 4. Poor batch and stream integration │──► Batch and stream integration is not supported, batch and stream need to be written separately
├─────────────────┤
│ 5. Poor monitoring │──► Real-time synchronization progress, synchronization rate, etc. cannot be seen
└─────────────────┘
Enter fullscreen mode Exit fullscreen mode

Market Solutions Analysis

  • Solution A: High performance but heavyweight deployment
  • Solution B: Lightweight but unstable, single-node
  • Solution C: High maintenance costs, inflexible

These limitations sparked the creation of SeaTunnel’s new engine — affectionately called “Ultraman Zeta” by the community for bringing light to data integration.

Architectural Evolution

Design Goals

We set audacious objectives:

  1. Performance: Trillion-record sync capability
  2. Usability: 5-minute setup, 30-minute deployment
  3. Extensibility: Connector development via minimal class implementations
  4. Stability: 24/7 operation
  5. Efficiency: 50%+ resource reduction vs alternatives

Core Architecture

After months of community collaboration:

┌───────────────────────────────────────────┐
│            SeaTunnel API Layer            │
├───────────────────────────────────────────┤
│          Plugin Discovery Layer           │
├───────────────────────────────────────────┤
│           Multi-Engine Support            │
│    ┌────────┐  ┌─────────┐  ┌────────┐   │
│    │ Flink  │  │  Spark  │  │  Zeta  │   │
│    └────────┘  └─────────┘  └────────┘   │
└───────────────────────────────────────────
Enter fullscreen mode Exit fullscreen mode

Technical Breakthroughs

1. Multi-Engine Support Evolution

Historical Context

2017-2019      →      2019-2021       →      2021-Present
Spark-only           +Flink Support           Zeta Engine
Enter fullscreen mode Exit fullscreen mode

Translation Layer Innovation

SeaTunnel API Layer
                   ▲
         Translation Layer
    ┌──────────┬──────────┬──────────┐
    │ Spark    │ Flink    │ Zeta     │
    │Translator│Translator│Translator│
    └──────────┴──────────┴──────────┘
Enter fullscreen mode Exit fullscreen mode

2. Intelligent Connection Pooling

Before

Table1 ─► Connection1
Table2 ─► Connection2 (100 tables = 100 connections)
Enter fullscreen mode Exit fullscreen mode

After

Tables ─► Dynamic Pool (100 tables ≈ 10 connections)
Enter fullscreen mode Exit fullscreen mode

3. Zero-Copy Data Transfer

Traditional

Source → Memory → Transform → Memory → Sink
Enter fullscreen mode Exit fullscreen mode

SeaTunnel

Source ═════► Transform ═════► Sink
Enter fullscreen mode Exit fullscreen mode

4. Adaptive Backpressure

Fast Producer    Slow Consumer
     │               │
     ▼               ▼
  [||||||||]  →  [|||] (Automatic throttling)
Enter fullscreen mode Exit fullscreen mode

5. Dynamic Thread Scheduling

Traditional Pool       SeaTunnel Pool
│││││││││││ (100)     │││││ (10-50 adaptive)
└─────────┘            └───┘
Enter fullscreen mode Exit fullscreen mode

6. Plugin Architecture

ClassLoader Isolation

Bootstrap CL → System CL → SeaTunnel CL → Plugin CL
Enter fullscreen mode Exit fullscreen mode

Loading Process

1. Scan Plugins → 2. Create Loaders → 3. Load Config → 4. Init
Enter fullscreen mode Exit fullscreen mode

War Stories

The Memory Leak Mystery
A persistent memory creep traced to special character handling — was found after 72 hours of stack analysis.

Phantom Data Phenomenon
Intermittent data duplicates caused by batch boundary conditions — solved with transaction isolation improvements.

Performance Cliff
40% throughput drops with specific data patterns — resolved through adaptive batching.

Epilogue

As Linus Torvalds said: “Talk is cheap. Show me the code.”

But today we say: “Code is cheap. Show me the value.”

SeaTunnel proves that elegant solutions emerge when solving real-world problems at scale. The true measure of technology lies not in its complexity, but in its ability to make developers’ lives easier.

Heroku

This site is built on Heroku

Join the ranks of developers at Salesforce, Airbase, DEV, and more who deploy their mission critical applications on Heroku. Sign up today and launch your first app!

Get Started

Top comments (0)

A Workflow Copilot. Tailored to You.

Pieces.app image

Our desktop app, with its intelligent copilot, streamlines coding by generating snippets, extracting code from screenshots, and accelerating problem-solving.

Read the docs

👋 Kindness is contagious

Please leave a ❤️ or a friendly comment on this post if you found it helpful!

Okay