I'm seen this problem with a SOCKS protocol module I wrote.
I'm including a patch that fixes this problem. It does what I mentioned below. In the input filter, it moves the buckets rather than creating a new brigade and then concatenate. In the output filter it splits the brigade after a flush bucket only if there are buckets after the flush.
+1 to the piece that affects core_output_filter. A small patch is often worth a thousand words.
I remember seeing that code do unneccessary splits when I was working on a fd leak on keepalive connections with multiple requests. The empty brigades caused my new code to blow up for a while, so I considered it a good test case at the time. But I agree, it shouldn't split off empty brigades when they are so easy to avoid.
I'll test and commit that part of it. Keep up the good work!
Greg
