Explain advanced distributed tracing architecture and observability pipelines in PHP systems.

Distributed tracing tracks requests across services, enabling visibility into latency, failures, dependencies, and system behavior in distributed architectures.

Monolithic systems are relatively easy to debug because requests remain inside a single process.

Microservices fundamentally change this. A single user request may traverse:

Without distributed tracing, debugging becomes nearly impossible.

Core observability pillars:

Numerical measurements over time. Examples:

Detailed event records.

End-to-end request visibility.

Distributed tracing concepts:

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