8 * 1024字节?这似乎完全合理,如果是这样,您的高磁盘 I/O 可能与并发请求有关。您是否考虑过实施某种带宽限制?这是我为我的框架phunction做的一个仅 PHP 的实现:
public static function Download($path, $speed = null, $multipart = false)
{
if (strncmp('cli', PHP_SAPI, 3) !== 0)
{
if (is_file($path) === true)
{
while (ob_get_level() > 0)
{
ob_end_clean();
}
$file = @fopen($path, 'rb');
$size = sprintf('%u', filesize($path));
$speed = (empty($speed) === true) ? 1024 : floatval($speed);
if (is_resource($file) === true)
{
set_time_limit(0);
session_write_close();
if ($multipart === true)
{
$range = array(0, $size - 1);
if (array_key_exists('HTTP_RANGE', $_SERVER) === true)
{
$range = array_map('intval', explode('-', preg_replace('~.*=([^,]*).*~', '$1', $_SERVER['HTTP_RANGE'])));
if (empty($range[1]) === true)
{
$range[1] = $size - 1;
}
foreach ($range as $key => $value)
{
$range[$key] = max(0, min($value, $size - 1));
}
if (($range[0] > 0) || ($range[1] < ($size - 1)))
{
ph()->HTTP->Code(206, 'Partial Content');
}
}
header('Accept-Ranges: bytes');
header('Content-Range: bytes ' . sprintf('%u-%u/%u', $range[0], $range[1], $size));
}
else
{
$range = array(0, $size - 1);
}
header('Pragma: public');
header('Cache-Control: public, no-cache');
header('Content-Type: application/octet-stream');
header('Content-Length: ' . sprintf('%u', $range[1] - $range[0] + 1));
header('Content-Disposition: attachment; filename="' . basename($path) . '"');
header('Content-Transfer-Encoding: binary');
if ($range[0] > 0)
{
fseek($file, $range[0]);
}
while ((feof($file) !== true) && (connection_status() === CONNECTION_NORMAL))
{
ph()->HTTP->Flush(fread($file, round($speed * 1024)));
ph()->HTTP->Sleep(1);
}
fclose($file);
}
exit();
}
else
{
ph()->HTTP->Code(404, 'Not Found');
}
}
return false;
}
上面的方法有一些小的依赖,它增加了一些不必要的功能,比如多部分下载,但你应该能够毫无问题地重用节流逻辑。
// serve file at 4 MBps (max)
Download('/path/to/file.ext', 4 * 1024);
您甚至可以在默认情况下更加慷慨,并$speed
根据您从第一个索引中获得的值减少sys_getloadavg()
以避免对 CPU 造成压力。