What are some best practices for managing headers in PHP scripts to ensure proper communication with the client during long processing times?

When processing time is long in PHP scripts, it's important to manage headers properly to ensure proper communication with the client. One way to do this is by sending periodic updates to the client using the `flush()` function to prevent timeouts and keep the connection alive. Additionally, setting appropriate headers like `Content-Type`, `Content-Length`, and `Connection` can help improve the overall performance and user experience.

// Set appropriate headers for long processing time
header('Content-Type: text/html');
header('Content-Length: ' . ob_get_length());
header('Connection: keep-alive');

// Flush output buffer to send data to the client
ob_flush();
flush();

// Long processing task
// Example: for loop to simulate processing
for ($i = 0; $i < 10; $i++) {
    echo "Processing step $i<br>";
    // Flush output buffer after each step
    ob_flush();
    flush();
    sleep(1); // Simulate processing time
}

echo "Processing complete!";