Explain advanced distributed tracing and observability architecture in PHP systems.

Distributed tracing tracks requests across multiple services to diagnose latency, failures, and system bottlenecks.

Modern distributed PHP systems involve dozens or hundreds of services. Traditional logs become insufficient for debugging.

Observability consists of three pillars:

Discrete textual events.

Numerical measurements over time.

End-to-end request journeys.

Distributed tracing architecture:

Each request receives unique identifiers.

Individual operations inside traces.

Examples:

Trace metadata flows across services.

4.…