# Production Engineering for Trading

Szymon Kopyciński · 23 September 2026



##  Production engineering

### Production

The live environment where a real system operates.

Because production trading systems trade real money, standards are much stricter than in research environments.

### Dev / Development

An environment where software is actively developed and tested.

### Staging

An environment that closely resembles production without being production.

### Simulation

A controlled representation of a real system.

Trading simulations attempt to reproduce markets, exchange behaviour, fills, latency and counterparties.

### Replay

Running previously recorded market data through a system again.

Replay is widely used for testing and debugging market-data and trading systems.

### Deterministic

A system that produces the same output whenever it receives the same input under the same conditions.

Determinism makes systems easier to test and debug, and makes replay reliable.

### Idempotent

An operation that has no additional effect when performed more than once after the first successful application.

Idempotency is important in distributed systems, where retries occur.

### State

Information a system currently holds in memory or storage.

An order book, open orders and positions are all examples of state.

### Stateless

A component that does not retain information between requests.

Stateless systems are easier to scale, but trading systems usually need substantial state.

### Source of truth

The authoritative system or dataset whose state is considered correct.

### Failover

Switching to a backup system after the primary system fails.

### Redundancy

Maintaining multiple systems or components so that one failure does not stop the overall service.

### High availability

Designing a system to remain operational despite failures.

### Fault tolerance

The ability of a system to continue operating correctly when components fail.

### Observability

The ability to understand what a system is doing from its outputs.

Common observability tools include metrics, logs, traces, dashboards and alerts.

### Metric

A numerical measurement collected from a system.

Examples include order rate, CPU usage, message latency, fill rate and packet loss.

### Log

A recorded description of events occurring within software.

Good logs are essential for reconstructing what happened during a trading incident.

### Audit log

A durable record of important actions or events.

Trading systems maintain detailed audit trails for orders and executions.

Part of [Glossary Index](/blog/glossary-index) · Previous: [Trading Systems & Market Connectivity](/blog/glossary-index/glossary-trading-systems-market-conn) · Next: [Useful Abbreviations](/blog/glossary-index/glossary-abbreviations)