Hi, I guess you're using a systemd-based distro. You should have a look at this thread https://www.mail-archive.com/haproxy@formilux.org/msg23867.html.
The patches were applied to 1.7, but apparently backported to 1.6.11 and 1.5.19 since. Now I have a clean termination of old processes, no more orphans, even when performing a ton of reloads. Pierre