Forum OpenACS Development: Two new AOLserver 4.0 bugs
Restart problems, multiple people reporting having to send a kill signal twice with a pause in between and/or kill -9. Sounds like a problematic and annoying bug but not a show-stopper for most people.
One or two people also seem to be reporting AOLserver 4 respawning infinite times until the box comes to a halt. It is somewhat unclear, but it appears that this is likely due to attempts to remotely exploit an as yet unpatched security bug AOLserver 4.0, and those (presumably unsuccessful) attempts had the effect of a DOS attack. Supposedly this hole is very difficult to exploit successfully, an it is thought that the bug does not exist in AOLserver 3.3+ad13, but AFAIK no one has double checked and verified that.
On a more pleasant note, Zoran recently announced some promising alternative Tcl interp initialization work giving reportedly 1/3 the memory footprint and 50 times faster thread startup than baseline in AOLserver 4.0.