fastcgi_finish_request
(PHP 5 >= 5.3.3, PHP 7)
fastcgi_finish_request — Flushes all response data to the client
Описание
boolean fastcgi_finish_request
( void
)
This function flushes all response data to the client and finishes the request. This allows for time consuming tasks to be performed without leaving the connection to the client open.
Возвращаемые значения
Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.
Коментарии
There are some pitfalls you should be aware of when using this function.
The script will still occupy a FPM process after fastcgi_finish_request(). So using it excessively for long running tasks may occupy all your FPM threads up to pm.max_children. This will lead to gateway errors on the webserver.
Another important thing is session handling. Sessions are locked as long as they're active (see the documentation for session_write_close()). This means subsequent requests will block until the session is closed.
You should therefore call session_write_close() as soon as possible (even before fastcgi_finish_request()) to allow subsequent requests and a good user experience.
This also applies for all other locking techniques as flock or database locks for example. As long as a lock is active subsequent requests might bock.
This is very poor man's approach to async execution.
Better relying on message queues to process something asynchronously.
Here are few example of how to using it.
The first is basic example.
<?php
$file = __DIR__ . '/text.txt';
if (is_file($file) && is_writable($file)) {
@unlink($file);
echo '<small style="color: #ccc;">' . $file . ' was deleted.</small><br>' . PHP_EOL;
}
echo '<p>Calling to <code>fastcgi_finish_request()</code>.</p>' . PHP_EOL;
echo '<p>If success, the file ' . $file . ' will be created.</p>' . PHP_EOL;
if (function_exists('fastcgi_finish_request')) {
fastcgi_finish_request();
} else {
echo '<p style="color: red;">This server does not support <code>fastcgi_finish_request()</code> function.</p>' . PHP_EOL;
echo 'Exit now.<br>' . PHP_EOL;
exit();
}
echo 'This line will be not echo out.<br>' . PHP_EOL;
file_put_contents($file, date('Y-m-d H:i:s') . PHP_EOL, FILE_APPEND);
?>
The file text.txt will be create if successfully.
==========================
The second is about execution timeout.
<?php
set_time_limit(5);
$file = __DIR__ . '/text.txt';
if (is_file($file) && is_writable($file)) {
@unlink($file);
echo '<small style="color: #ccc;">' . $file . ' was deleted.</small><br>' . PHP_EOL;
}
echo '<p>Testing timeout and <code>fastcgi_finish_request()</code> function.</p>' . PHP_EOL;
echo '<p>Set timeout to ' . ini_get('max_execution_time') . ' seconds.</p>' . PHP_EOL;
echo '<p>Calling to <code>fastcgi_finish_request()</code>.</p>' . PHP_EOL;
echo '<p>If success, the file ' . $file . ' will be created but error will be shown in the log.</p>' . PHP_EOL;
if (function_exists('fastcgi_finish_request')) {
fastcgi_finish_request();
} else {
echo '<p style="color: red;">This server does not support <code>fastcgi_finish_request()</code> function.</p>' . PHP_EOL;
echo 'Exit now.<br>' . PHP_EOL;
exit();
}
$i = 1;
while(true){
if ($i <= 10) {
file_put_contents($file, date('Y-m-d H:i:s') . PHP_EOL, FILE_APPEND);
$i++;
}
//to infinity and beyond...
}
?>
I found that the code will be working as long as it is not reach timeout setting in php.ini or set_time_limit() function.
mike@php.net decided this https://bugs.php.net/bug.php?id=68772 is "not a bug" however be warned:
If you write to the buffer (using print statements, etc.) after calling fastcgi_finish_request(), your script will exit with no error message or exception. Calling ignore_user_abort(true) after fastcgi_finish_request() can mitigate this issue.