Managing PHP-FPM Slow Logs

PHP-FPM slowlog captures stack traces for requests exceeding a pool threshold.

What It Does and When to Use It

Set parameters in the FPM pool configuration; avoid exposing pool status publicly. The web server handles HTTP, the PHP worker executes scripts, and CLI has separate configuration and lifecycle.

Requirements, Inputs and Expected Behavior

Confirm the runtime, extension, environment variables, and permissions before running the examples in production. Slowlog paths must be writable by FPM and protected against public access.

Example 1: Basic Operation

Set parameters in the FPM pool configuration; avoid exposing pool status publicly.

request_slowlog_timeout = 5s
slowlog = /var/log/php-fpm/slow.log
request_terminate_timeout = 30s

Example 2: Behavior and Validation

Run the matching status or validation command on the intended host.

tail -n 50 /var/log/php-fpm/slow.log

Practical Example: Application Use

Correlate capacity, worker crashes and slow requests using logs and process state.

sudo systemctl status php8.4-fpm --no-pager
sudo journalctl -u php8.4-fpm -n 35 --no-pager

Important Behavior and Edge Cases

The second example highlights: Run the matching status or validation command on the intended host. The practical example adds: Correlate capacity, worker crashes and slow requests using logs and process state.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• PHP-FPM slowlog captures stack traces for requests exceeding a pool threshold.
• Correlate capacity, worker crashes and slow requests using logs and process state.
• Check the effective configuration in the SAPI serving requests before changing production.