PHP SAPI Types (FPM, CLI, Embed)

TL;DR

Explanation

PHP SAPIs: php-fpm (FastCGI Process Manager) — long-running pool of workers handling web requests, separate PHP-FPM pool config, per-request memory reset. php-cli — single execution, unlimited max_execution_time by default, used for scripts, cron, queues. php-cgi — legacy CGI, spawned per request. apache2handler — mod_php embedded in Apache. embed — PHP embedded in C apps. php_sapi_name() returns the SAPI name. Key differences: superglobals ($_SERVER, $_REQUEST) only populated in web SAPIs. STDIN/STDOUT available in CLI. php-fpm pools can have per-pool php.ini overrides. Workers share nothing between requests — no state persistence without external storage (Redis, DB).

Common Misconception

Why It Matters

Common Mistakes

• Using CLI-only functions (readline, pcntl) in web context.
• Not setting different memory_limit/max_execution_time per SAPI.
• Assuming $_SERVER is populated in CLI scripts.

Code Examples

// In web request — reads from stdin, only works in CLI:
$input = fgets(STDIN); // Returns false in FPM

// SAPI detection:
if (PHP_SAPI === 'cli') {
    $input = fgets(STDIN);
} else {
    $input = $_POST['data'] ?? '';
}

// Check in code:
echo PHP_SAPI; // 'fpm-fcgi', 'cli', 'apache2handler' etc

References

• ↗ https://www.php.net/manual/en/function.php-sapi-name.php

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