20 Rules to Optimize PHP for High-Traffic Websites

Certainly! Optimizing PHP for high-traffic websites requires a comprehensive approach that spans code quality, database management, caching, server configuration, and much more. Below is an extensive list of rules to optimize PHP for high-traffic websites, with hands-on examples included where applicable.

1. Use Opcode Caching

Rule: Enable OPcache to cache precompiled PHP code.

Example:

; Enable OPcache in php.ini
opcache.enable=1
opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=10000
opcache.revalidate_freq=60

2. Optimize Database Queries

Rule: Use indexed columns and avoid unnecessary columns in SELECT statements.

Example:

-- Instead of SELECT *
SELECT id, name, price FROM products WHERE category_id = 1;

3. Implement Data Caching

Rule: Cache frequently accessed data with Memcached.

Example:

$memcached = new Memcached();
$memcached->addServer('localhost', 11211);
$key = 'products_list';
$products = $memcached->get($key);

if ($products === FALSE) {
    $products = get_products_from_database(); // Fetch from DB
    $memcached->set($key, $products, 600); // Cache for 10 minutes
}

4. Use Persistent Connections

Rule: Use persistent database connections to reduce connection overhead.

Example:

$pdo = new PDO('mysql:host=localhost;dbname=test', 'user', 'password', [
    PDO::ATTR_PERSISTENT => true
]);

5. Reduce File I/O Operations

Rule: Minimize file system reads/writes.

Example:

// Avoid repeated file reads
$settings = include('config.php'); // Cache this in a variable if used multiple times

6. Optimize PHP Configuration

Rule: Adjust php.ini settings for better performance.

Example:

memory_limit=256M
max_execution_time=30

7. Use Autoloaders

Rule: Use Composer's autoloader for efficient class loading.

Example:

require 'vendor/autoload.php'; // Composer's autoloader

// Use classes
$object = new MyClass();

8. Implement Load Balancing

Rule: Distribute traffic across multiple servers.

Example:

• Configure Nginx for load balancing:

http {
    upstream backend {
        server backend1.example.com;
        server backend2.example.com;
    }

    server {
        location / {
            proxy_pass http://backend;
        }
    }
}

9. Use Asynchronous Processing

Rule: Offload tasks to background processes.

Example:

// Using a queue system like Redis
$redis = new Redis();
$redis->connect('localhost');
$redis->rPush('email_queue', json_encode($emailData));

// Worker process to handle email sending
$emailData = json_decode($redis->lPop('email_queue'), true);
send_email($emailData);

10. Minimize Dependencies

Rule: Only include necessary libraries and dependencies.

Example:

composer install --no-dev // Install production dependencies only

11. Optimize Loops and Algorithms

Rule: Avoid inefficient loops and algorithms.

Example:

// Instead of inefficient loops
foreach ($items as $item) {
    // Process item
}

// Use optimized algorithms and data structures
$items = array_map('processItem', $items);

12. Use Efficient Data Structures

Rule: Choose appropriate data structures for your needs.

Example:

// Using associative arrays for quick lookups
$data = ['key1' => 'value1', 'key2' => 'value2'];
$value = $data['key1'];

13. Optimize Session Handling

Rule: Use efficient session storage.

Example:

; Use Redis for session storage
session.save_handler = redis
session.save_path = "tcp://localhost:6379"

14. Use HTTP/2

Rule: Take advantage of HTTP/2 for better performance.

Example:

• Configure HTTP/2 in Nginx:

server {
    listen 443 ssl http2;
    # Other SSL configuration
}

15. Implement Gzip Compression

Rule: Compress responses to reduce bandwidth.

Example:

• Enable Gzip in Nginx:

http {
    gzip on;
    gzip_types text/plain text/css application/json application/javascript;
}

16. Minimize Frontend Asset Size

Rule: Optimize CSS, JavaScript, and image files.

Example:

# Minify CSS and JS files
uglifyjs script.js -o script.min.js

17. Use a Content Delivery Network (CDN)

Rule: Offload static content to a CDN.

Example:

• Configure CDN for static assets:

<link rel="stylesheet" href="https://cdn.example.com/styles.css">
<script src="https://cdn.example.com/scripts.js"></script>

18. Enable Error Logging

Rule: Log errors efficiently for debugging.

Example:

; Log errors to a file
error_log = /var/log/php_errors.log
log_errors = On

19. Monitor Performance

Rule: Use monitoring tools to track performance.

Example:

• Install and configure New Relic:

# Install New Relic PHP agent
sudo newrelic-install install

# Configure New Relic in php.ini
newrelic.enabled = true

20. Regularly Profile and Benchmark

Rule: Continuously profile and benchmark your application.

Example:

• Use Xdebug to profile PHP scripts:

# Install Xdebug
sudo pecl install xdebug

# Enable Xdebug profiling in php.ini
xdebug.profiler_enable = 1
xdebug.profiler_output_dir = "/tmp/xdebug"

By following these rules and implementing the provided examples, you can significantly enhance the performance and scalability of PHP-based high-traffic websites.