I encountered hanging feof resulting in StreamException("The stream was closed by the peer").
This happens when doing requests in Kubernetes to Facebook.

Omitting the feof check "fixes" it.

A workaround (and better code) would be to not check on @feof before the write but setting an error handler for the fwrite and cathing warnings and converting them to stream exceptions.

Example:

                    $eh = set_error_handler([$this, 'onSocketWriteError']);
                    
                    if ($chunkSize) {
                        $written = \fwrite($stream, $data, $chunkSize);
                    } else {
                        $written = \fwrite($stream, $data);
                    }

                    set_error_handler($eh);