I'm using VirtualBox 3.2.8_OSE with 20 VMs running, and everything's going fine.

I find that if I hammer the VBoxManage interface, all sorts of interesting things happen, usually necessitating either a restart of the VM in question, or of all VMs.

For instance, if I use VBoxManage guestcontrol execute to run processes, after a few hours of using it maybe once or twice a minute on any given VM, it'll mysteriously start reporting VERR_NOT_IMPLEMENTED and refusing to do anything—sometimes trying to restart /usr/sbin/VBoxService on the VM itself will get it back in working order, but often it won't, and in the meantime, no data can be collected using VBoxManage. Such data includes the VM's IP, so if I hadn't recorded it earlier, I'm usually in trouble and have no option but to portscan the network for it, or kill the VM's process on the host manually and restart it.

This one I haven't narrowed down yet, but it seems that even using VBoxManage guestproperty get (to retrieve a machine's IP) frequently and rapidly is enough to cause all VMs' management interfaces to die. The processes are still running fine, but VBoxManage reports them all as "powered off". In the meantime, another process somewhere in the system seems to have decided that their being powered off means they need to be powered on again, and suddenly I have 2x the number of VBoxHeadless processes running than I used to.

Has anyone else seen behaviour like this? Is there any workaround? This is a serious impediment to my work, as I've had to resort to a lot of (hacky) caching of data and rate-limiting how often I call VBoxManage, just in case I accidentally bring 20 VMs to their knees.