Optimize Docker Opcache

OPcache Configuration Optimization

Provides production and development OPcache tuning for PHP Docker containers, including JIT and preloading.

OPcache Impact Overview

┌─────────────────────────────────────────────────────────────────┐
│                  OPCACHE PERFORMANCE IMPACT                      │
├─────────────────────────────────────────────────────────────────┤
│  Without OPcache:                                               │
│  Request → Parse → Compile → Execute → Response      ~50ms     │
│  With OPcache:                                                  │
│  Request → Execute (cached bytecode) → Response      ~15ms     │
│  With OPcache + JIT:                                            │
│  Request → Execute (native code) → Response          ~10ms     │
│  With OPcache + JIT + Preload:                                  │
│  Request → Execute (preloaded) → Response             ~5ms     │
└─────────────────────────────────────────────────────────────────┘

Production vs Development Settings

Memory Consumption Calculation

memory_consumption = total_php_files * avg_bytecode_size (20-50 KB per file)

  Small project (500 files):    15MB  → set 64MB
  Medium project (2000 files):  60MB  → set 128MB
  Large project (5000 files):  175MB  → set 256MB
  Enterprise (10000+ files):   350MB  → set 512MB

max_accelerated_files Calculation

PHP rounds up to the next prime from: 223, 463, 983, 1979, 3907, 7963, 16229, 32531, 65407, 130987

JIT Configuration (PHP 8.0+)

opcache.jit = CRTO (4-digit mode)
  C: CPU optimization (0=off, 1=on)
  R: Register allocation (0=off, 1=local, 2=global)
  T: Trigger (0=first run, 3=hot counter, 5=tracing)
  O: Optimization (0=none, 5=full)

Preloading (PHP 7.4+)

<?php
// config/preload.php
$directories = [
    '/app/src/Domain/', '/app/src/Application/',
    '/app/vendor/symfony/http-kernel/',
];
foreach ($directories as $dir) {
    if (!is_dir($dir)) continue;
    $it = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($dir, FilesystemIterator::SKIP_DOTS)
    );
    foreach ($it as $file) {
        if ($file->getExtension() === 'php') opcache_compile_file($file->getRealPath());
    }
}

Monitoring OPcache

Production OPcache INI

[opcache]
opcache.enable = 1
opcache.enable_cli = 1
opcache.memory_consumption = 256
opcache.interned_strings_buffer = 32
opcache.max_accelerated_files = 20000
opcache.validate_timestamps = 0
opcache.revalidate_freq = 0
opcache.save_comments = 1
opcache.fast_shutdown = 1
opcache.jit = 1255
opcache.jit_buffer_size = 128M
opcache.preload = /app/config/preload.php
opcache.preload_user = www-data
opcache.log_verbosity_level = 1
opcache.error_log = /proc/self/fd/2

Development OPcache INI

[opcache]
opcache.enable = 1
opcache.enable_cli = 0
opcache.memory_consumption = 128
opcache.interned_strings_buffer = 16
opcache.max_accelerated_files = 10000
opcache.validate_timestamps = 1
opcache.revalidate_freq = 2
opcache.save_comments = 1
opcache.jit = disable
opcache.jit_buffer_size = 0

Dockerfile Integration

ARG APP_ENV=production
COPY docker/php/opcache-${APP_ENV}.ini /usr/local/etc/php/conf.d/opcache.ini
COPY config/preload.php /app/config/preload.php

Before/After Comparison

Generation Instructions

1. Count PHP files: find /app -name "*.php" | wc -l (including vendor)
2. Calculate memory: files * 35KB, round up to nearest power of 2
3. Set max_accelerated_files: Next prime above file count
4. Configure JIT: 1255 for production, disable for development
5. Create preload script: Include domain, application, and framework core
6. Set validate_timestamps: 0 for immutable containers, 1 for development
7. Monitor: Check hit rate and memory usage after deployment

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