Caching Strategies for PHP
Fetching data from a database or performing expensive computations on every request slows down your application. Caching stores results for future use, reducing latency and server load. You can cache at several layers.
Opcode caching
OpCache, bundled with modern PHP, caches compiled bytecode in memory. Ensure it's enabled in your php.ini:
[opcache]
opcache.enable=1
opcache.memory_consumption=128
opcache.max_accelerated_files=10000
opcache.revalidate_freq=60
This dramatically reduces CPU usage by avoiding repeated compilation.
Data caching
For transient data, use APCu or Memcached. APCu stores variables in shared memory inside the PHP process:
<?php
declare(strict_types=1);
// compute result
$result = apcu_fetch('expensive_result');
if ($result === false) {
$result = some_heavy_function();
apcu_store('expensive_result', $result, 300); // cache for 5 minutes
}
echo $result;
?>
Memcached or Redis provide a centralised cache accessible by multiple servers. Abstract caching behind an interface so you can swap implementations later.
Application caching
Cache entire rendered pages or fragments to avoid rebuilding markup. Use reverse proxies like Varnish or micro caching in your application framework. Always invalidate caches when underlying data changes.