Just to add some detail to Talli's post about our experience with OpenACS on FreeBSD (actually, of course, the issue is AOLServer on FreeBSD):
- AOLServer will compile and run (mostly) fine on FreeBSD. The problem is with the tcl "exec" command, which executes whatever command is called from it, but returns an incorrect value. This causes programs to return an error page, even though the command has executed properly, thereby causing confusion, alarm, and despair. The folks at AOLServer have assured me that this will be fixed Real Soon Now.
- As a workaround, we tried running AOLServer on FreeBSD under Linux emulation. This is where we ran into the problems Talli was talking about. In this mode, threads do not exit properly, filling the process table with thousands of zombie processes, many of which hold locks on core that can't be released except by a reboot.
As soon as I get to a point where I feel comfortable taking on additional responsibilities, I will volunteer with the OpenNSD project to try and clear up *BSD related bugs. The AOLServer team apparently focuses their development efforts on Solaris and Linux, and supporting other platforms is not a high priority for them.