Explain Linux process management and PHP-FPM internals for high-scale systems.

PHP-FPM manages pools of worker processes that execute PHP scripts efficiently under high concurrency.

PHP applications in production commonly run through PHP-FPM (FastCGI Process Manager). Understanding PHP-FPM internals is critical for designing scalable infrastructure.

PHP is traditionally request-based:

This architecture provides isolation but introduces process-management complexity.

Core PHP-FPM concepts:

Responsible for:

2.…