@chaizhenhua 
It would be nice if we respected upstream flushes. So, if our module receives a flush, we also flush ourselves within a reasonable timespan. Consider this example:

`curl --raw  http://www.iispeed.com/flush`

If we don't respect flushes in cases like that, we may cause a perceived slowdown for end users, as they will only receive any bytes after the final flush.
I'm OK with this as it is now, but I would like to look into that later, after we have this pull merged.