Multiple libguestfs appliances in parallel, part 2

One problem with the previous test is that I hit a limit of 20 parallel appliances and mistakenly thought that I’d hit a memory limit. In fact libvirt out of the box limits the number of client connections to 20. You can adjust libvirt’s limit by editing /etc/libvirt/libvirtd.conf, but easier for us is to simply eliminate libvirt from the equation by doing:

export LIBGUESTFS_ATTACH_METHOD=appliance

which causes libguestfs to run qemu directly. In my first test I reached 48 parallel launches before I killed the program (because that’s a lot of parallelism and there seemed no end in sight). Scalability of the libguestfs / qemu combination was excellent again:

But there’s more! (In the next part …)