This morning, I found another case where haproxy 2.0 abnormally consumes
the cpu. It occured on my laptop when my network was not setup yet.
I could find a simple reproducer :
server s1 10.0.0.1:8888
then, curl http://localhost:8888/
10.0.0.1 is unreachable and the connection stays in SYN_SENT, but
haproxy progressively raises to 100% CPU even after stopping curl.
running a second curl will raise the CPU up to 200%, etc...
I think I'll have time to investigate tonight but maybe you'll find the
issue and the fix before me ;)
It looks to be very specific to the 2.0 branch, I can't reproduce it in
1.9 and 2.1.