[libvirt] [PATCH v2] libvirt-guests: Add parallel startup and shutdown of guests

[Peter Krempa]

On 03/03/2012 03:03 AM, Eric Blake wrote:
> On 03/01/2012 07:23 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.
>> ---
>
>> +# shutdown_guests_parallel URI GUESTS
>> +# Shutdown guests GUESTS on machine URI in parallel
>> +shutdown_guests_parallel()
>> +{
>> +    uri=$1
>> +    guests=$2
>> +
>> +    on_shutdown=
>
> check_timeout=false
>
>> +    timeout=$SHUTDOWN_TIMEOUT
>
> if [ $timeout -gt 0 ]; then
>      check_timeout=true
> fi
>
>> +    while [ -n "$on_shutdown" ] || [ -n "$guests" ]; do
>> +        while [ -n "$guests" ]&&
>> +              [ $(guest_count "$on_shutdown") -lt "$PARALLEL_SHUTDOWN" ]; do
>> +            set -- $guests
>> +            guest=$1
>> +            shift
>> +            guests=$*
>> +            shutdown_guest_async "$uri" "$guest"
>> +            on_shutdown="$on_shutdown $guest"
>> +        done
>> +        sleep 1
>
> if $check_timeout; then
>
>> +        timeout=$(($timeout - 1))
>> +        if [ $timeout -le 0 ]; then
>> +            eval_gettext "Timeout expired while shutting down domains"; echo
>> +            RETVAL=1
>> +            return
>> +        fi
>
> fi
>
>> +        on_shutdown_prev=$on_shutdown
>> +        on_shutdown=$(check_guests_shutdown "$uri" "$on_shutdown")
>> +        print_guests_shutdown "$uri" "$on_shutdown_prev" "$on_shutdown"
>> +    done
>> +}
>> +
>
>>
>> -# number of seconds we're willing to wait for a guest to shut down
>> +# If set to non-zero, shutdown will suspend guests concurrently. Number of
>> +# guests on shutdown at any time will not exceed number set in this variable.
>> +#PARALLEL_SHUTDOWN=0
>> +
>> +# Number of seconds we're willing to wait for a guest to shut down. If parallel
>> +# shutdown is enabled, this timeout applies as a timeout for shutting down all
>> +# guests on a single URI defined in the variable URIS. This must be set to
>> +# a nonzero positive value if the shutdown action is requested.
>
> Change the last sentence:
>
> If this is 0, then there is no time out (use with caution, as guests
> might not respond to a shutdown request).  (Hmm, maybe we want to
> default to 300 [5 minutes], and document our non-zero default, so that
> you have to explicitly request 0 to avoid timeouts.)
>
> ACK with those lines added to shutdown_guests_parallel, and the wording
> change to the config file, and with the optional change to the timeout
> default.
>

The same check for the timeout was also needed in shutdown_guest(). I 
added the checks, changed the wording in the config file and set the 
default SHUTDOWN_TIMEOUT to 300 (with a note in the docs) and pushed the 
result.

Thanks

Peter