Re: [libvirt] [PATCH 4/4] libvirt-guests: Add parallel startup and shutdown of guests
On 02/28/2012 11:00 AM, Peter Krempa wrote:
With this patch, it's possible to shut down guests in parallel.
Parallel
startup was possible before, but this functionality was not documented
properly.
To enable parallel startup set the START_DELAY to 0.
Parallel shutdown has a configurable parameter PARALLEL_SHUTDOWN that
defines the number of machines being shut down in parallel. Enabling
this feature changes the semantics of SHUTDOWN_TIMEOUT parameter that is
applied as a cumulative timeout to shutdown all guests on a URI.
---
tools/libvirt-guests.init.sh | 140 +++++++++++++++++++++++++++++++++++++++--
tools/libvirt-guests.sysconf | 10 +++-
2 files changed, 141 insertions(+), 9 deletions(-)
Missing an initialization of PARALLEL_SHUTDOWN=0 alongside
SHUTDOWN_TIMEOUT=0 before sourcing the user's values.
+
+# check_domains_shutdown URI GUESTS
+# check if shutdown is complete on guests in "GUESTS" and returns only
+# guests that are still shutting down
+check_domains_shutdown()
+{
+ uri=$1
+ guests=$2
+
+ guests_up=
+ for guest in $guests; do
+ guest_is_on "$uri" "$dom" 2>&1 > /dev/null ||
continue
You want '>/dev/null 2>&1' (order matters, when silencing a command and
using it just for its side effects). But are we sure we want to
silently ignore a guest_is_on failure, or should we emit a message
stating that we are no longer able to track the shutdown status of that
guest?
+print_domains_shutdown()
+{
+ uri=$1
+ before=$2
+ after=$3
+
+ for guest in $before; do
+ found=false
+ for running in $after; do
+ if [ $guest = $running ]; then
+ found=true
+ break
+ fi
+ done
slightly faster to do:
for guest in $before; do
found=false;
case " $after " in
*" $guest "*) found=true ;;
esac
But what you have is functionally correct.
+
+ if ! "$found"; then
+ name=$(guest_name "$uri" "$guest")
+ eval_gettext "Shutdown of guest \$name complete."
+ echo
+ fi
+ done
+}
+
+# shutdown_guests_parallel URI GUESTS
+# Shutdown guests GUESTS on machine URI in parallel
+shutdown_guests_parallel()
+{
+ uri=$1
+ guests=$2
+
+ on_shutdown=
+ timeout=$SHUTDOWN_TIMEOUT
If SHUTDOWN_TIMEOUT is the default of 0, then this function times out
right away; shouldn't that really mean that we have no maximum timeout,
and wait until everything has shut down? I think you need another
variable, based on whether $timeout is 0 on entry, and skip the
$((timeout - 1)) calculation if that variable is true.
+ while [ -n "$on_shutdown" ] || [ -n
"$guests" ]; do
+ while [ -n "$guests" ] &&
+ [ $(guest_count "$on_shutdown") -lt
"$PARALLEL_SHUTDOWN" ]; do
+ guest=$(guest_first $guests)
+ guests=$(guest_remove "$guest" "$guests")
Faster to avoid these two sub-shells by doing:
set -- $guests
guest=$1
shift
guests=$*
and might even get rid of the need for some helper functions. But what
you have is functionally correct.
@@ -23,7 +24,12 @@
# value suitable for your guests.
#ON_SHUTDOWN=suspend
-# number of seconds we're willing to wait for a guest to shut down
+# If set to non-zero, shutdown will suspend domains concurently. Number of domains
s/concurently/concurrently/
I think it's probably worth a v2 (or is it v3?) for just this patch.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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