What common pitfalls should developers be aware of when writing asynchronous PHP code with Swoole, particularly around shared state and blocking calls?

Common pitfalls include accidentally calling a traditional blocking PHP function, such as the standard file_get_contents, from within a coroutine, which blocks the entire worker process rather than yielding control as intended, and improperly managing shared state between coroutines, since unlike traditional PHP where each request gets a completely fresh process, a long running Swoole worker process shares memory across many requests, meaning global variables or static properties can leak state between requests if not carefully managed.

// Problematic: blocks the entire worker
$data = file_get_contents($url);

// Correct: use Swoole's coroutine compatible HTTP client
$data = Swoole\Coroutine\Http\request($url);