Header issue with fpm and php 8.4

[oliverspecht]

Hi,
i am reaching out as I found your repository and also are running an old symfony 1.4 version. Really appreciate your work and found some updates I could integrate. Thanks for that.

I am currently trying to update to PHP 8.4 and have an error which I could track down to some changes in the 8.4.1 version regarding the fastcgi flush behaviour: php/php-src#12385

I am running symfony in the php:8.4-fpm-bullseye docker image.

The error I get is:
Cannot modify header information - headers already sent

Previously when the sfWebResponse::send() method was called, the headers weren't sent until fastcgi_finish_requests() was called. Now, if I use the console logger (which writes to stdout) the headers are already sent before sendHttpHeaders() method call. I debugged this by simply doing

public function send()
{
   error_log('pre headers sent: '.(headers_sent() ? 'true' : 'false'));
   $this->sendHttpHeaders();
   error_log('post headers sent: '.(headers_sent() ? 'true' : 'false'));
   $this->sendContent();
   if (function_exists('fastcgi_finish_request')) {
     $this->dispatcher->notify(new sfEvent($this, 'response.fastcgi_finish_request'));
     fastcgi_finish_request();
   }
   error_log('post post headers sent: '.(headers_sent() ? 'true' : 'false'));
}

And for 8.3 I get:

PHP message: pre headers sent: false
PHP message: post headers sent: false
PHP message: post post headers sent: true

For 8.4 I get:

PHP message: pre headers sent: true
PHP message: post headers sent: true
PHP message: post post headers sent: true

Is there anyone who has an idea? Would really be appreciated. It seems it is only about the console logger as other requests seem to run fine.

UPDATE

If I remove the flush() call from the doLog() method it seems to work but I am not sure if I can rely on flush always happening later. And so it seems the issue might not be related to the fastcgi fix...

    protected function doLog($message, $priority)
    {
        fwrite($this->stream, $message.PHP_EOL);
        // flush();
    }