Lighttpd

Hi, all

I found a serious problem.
I wrote a C program which sends a HTTP request to lighttpd very slowly, one byte each second (write 1 bytes, then sleep 1 second).

And I also wrote a shell script as below:

##slow_test.sh
for ((j=0;j<1000;j++)) do
  for ((i=0; i<50; i++)) do
  ## slow_client is a C program which sends a HTTP request very slowly
    ./slow_client http://xxx.xxx.xxx.xxx:8080/>/dev/null 2>/dev/null &
  done&
  sleep 3
done

I started slow_test.sh. After a few minutes, lighttpd had occupied much memory, and finally all of 4G memory was exhausted, the server machine was unable to serve any more.

I read the source code, and found lighttpd will allocate a new chunk(16384 bytes) every time for the new request data which triggered by the event FDEVENT_IN. But the problem is, once FDEVENT_IN arrives, the new data is always stored in a new chunk, no matter how many bytes have been received at the monent. So it will be a waste of memory.

I suggest stroring request bytes in a compact way. If last chunk is not full, new data should be put into the last chunk. I submit my patch(based on lighttpd 1.5.0 svn r2700) in attachment.

Thanks

Ming, Li