PHP-FPM Configuration Optimization

Provides production-ready PHP-FPM tuning for Docker containers based on workload type and available resources.

Process Manager Modes

┌─────────────────────────────────────────────────────────────────┐
│                  PHP-FPM PROCESS MANAGERS                        │
├─────────────────────────────────────────────────────────────────┤
│  STATIC:    [W][W][W][W][W][W][W][W]   Fixed pool              │
│             Best for: dedicated containers, predictable load    │
│  DYNAMIC:   [W][W][W][W][ ][ ][ ][ ]   Scales up/down         │
│             Best for: variable load, shared resources           │
│  ONDEMAND:  [ ][ ][ ][ ][ ][ ][ ][ ]   Starts on request      │
│             Best for: low-traffic, dev environments             │
└─────────────────────────────────────────────────────────────────┘

Memory Calculation Formula

max_children = (available_memory - system_overhead) / avg_worker_memory

Where:
  available_memory = container_memory_limit
  system_overhead  = ~50MB (OS + PHP-FPM master + nginx)
  avg_worker_memory = 30-60MB (depends on application)

Container Memory	System Overhead	Worker Memory	max_children
256MB	50MB	40MB	5
512MB	50MB	40MB	11
1024MB	50MB	40MB	24
2048MB	50MB	50MB	39

Measure actual worker memory:

ps aux | grep "php-fpm: pool" | awk '{sum+=$6; n++} END {print sum/n/1024 " MB"}'

Configuration by Workload

API Workload (Many Fast Requests)

[www]
pm = static
pm.max_children = 20
request_terminate_timeout = 30s
request_slowlog_timeout = 5s
pm.max_requests = 1000
slowlog = /proc/self/fd/2

Worker Workload (Few Long Requests)

[www]
pm = dynamic
pm.max_children = 8
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 4
request_terminate_timeout = 300s
request_slowlog_timeout = 30s
pm.max_requests = 200

Mixed Workload

[www]
pm = dynamic
pm.max_children = 15
pm.start_servers = 5
pm.min_spare_servers = 3
pm.max_spare_servers = 8
request_terminate_timeout = 60s
request_slowlog_timeout = 10s
pm.max_requests = 500

Dynamic Mode Formulas

pm.start_servers     = (min_spare + max_spare) / 2
pm.min_spare_servers = max_children * 0.25
pm.max_spare_servers = max_children * 0.75

pm.max_requests by Application Type

Application Type	Recommended Value
Stateless API	1000-5000
Framework with ORM	500-1000
Legacy application	100-500
Memory-intensive processing	50-200

Health Check and Monitoring

pm.status_path = /status
ping.path = /ping
ping.response = pong

HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
    CMD php-fpm-healthcheck || exit 1

Key status metrics to monitor:

• active processes: current load
• listen queue: requests waiting (should be 0)
• max children reached: need more workers
• slow requests: performance issues

Docker-Specific Settings

; Logging to stdout/stderr
error_log = /proc/self/fd/2
access.log = /proc/self/fd/2
clear_env = yes
catch_workers_output = yes
decorate_workers_output = no

Before/After Comparison

Metric	Default	Optimized (static)	Improvement
max_children	5	20	+300% capacity
Idle memory (512MB)	200MB wasted	~50MB overhead	-75% waste
Request latency (p99)	500ms	150ms	-70%
Throughput (req/s)	50	200	+300%
Memory leak recovery	Never	Every 1000 req	Predictable

Complete Production Configuration

[global]
error_log = /proc/self/fd/2
log_level = warning
daemonize = no

[www]
user = www-data
group = www-data
listen = 0.0.0.0:9000
pm = static
pm.max_children = 20
pm.max_requests = 1000
request_terminate_timeout = 30s
request_slowlog_timeout = 5s
slowlog = /proc/self/fd/2
pm.status_path = /status
ping.path = /ping
ping.response = pong
clear_env = yes
catch_workers_output = yes
decorate_workers_output = no
access.log = /proc/self/fd/2
access.format = "%R - %u %t \"%m %r\" %s %{mili}dms %{mega}MMB %C%%"

Generation Instructions

1. Determine workload type: API, Worker, or Mixed
2. Calculate max_children: Based on container memory and worker memory
3. Select PM mode: Static for production, dynamic for variable load
4. Configure timeouts: Based on expected request duration
5. Set max_requests: Based on application memory behavior
6. Enable monitoring: Status page, health check, slow log