Re: virtlogd spinning on 100% CPU with the latest libvirt
[Dropped Peter from CC. Please don't CC individual developers
unless they've explicitly requested that you do so.]
On Mon, 2020-02-17 at 17:50 +0000, Richard W.M. Jones wrote:
Build libvirt from git (ccf7567329f).
Using the libvirt ‘run’ script, run something like
libguestfs-test-tool. I think basically any command which runs a
guest will do. NB These commands are all run as NON-root:
killall libvirtd lt-libvirtd virtlogd lt-virtlogd
./build/run libguestfs-test-tool
Now there will be a lt-virtlogd process using 100% of CPU:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2572972 rjones 20 0 47880 16256 14516 R 100.0 0.1 0:19.27 lt-virt+
It's actually worse than that: not only virtlogd usese an
unwarranted amount of CPU, but it also keeps the log file for the
domain busy, thus preventing the same domain from being started
again:
$ virsh start alpine
Domain alpine started
$ virsh destroy alpine
Domain alpine destroyed
$ virsh start alpine
error: Failed to start domain alpine
error: can't connect to virtlogd: Cannot open log file:
'/var/log/libvirt/qemu/alpine.log': Device or resource busy
$ sudo lsof | grep alpine.log
virtlogd 146845 root 16w REG 253,0 35103
17195654 /var/log/libvirt/qemu/alpine.log
$
Restarting virtlogd makes thing operational again:
$ sudo systemctl restart virtlogd
$ virsh start alpine
Domain alpine started
$
My guess is that virtlogd doesn't realize the QEMU process is gone,
and sits there spinning forever waiting for some output that will
never arrive.
--
Andrea Bolognani / Red Hat / Virtualization