Re: [libvirt] [PATCH v2] lib: Add note that bulk stats API queries may overrun RPC buffers

On Tue, May 23, 2017 at 04:23:30PM +0200, Peter Krempa wrote: > Hint that the users should limit the number of VMs queried in the bulk > stats API. > --- > v2: > - added a suggestion of the number of queried VMs (valid after bump to > 32M message) > > src/libvirt-domain.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c > index 310b91b37..aef061943 100644 > --- a/src/libvirt-domain.c > +++ b/src/libvirt-domain.c > @@ -11315,6 +11315,10 @@ virConnectGetDomainCapabilities(virConnectPtr > conn, > * VIR_CONNECT_GET_ALL_DOMAINS_STATS_SHUTOFF and/or > * VIR_CONNECT_GET_ALL_DOMAINS_STATS_OTHER for all other states. > * > + * Note that this API is prone to exceeding maximum RPC message size > on hosts > + * with lots of VMs so it's suggested to use virDomainListGetStats > with a > + * reasonable list of VMs as the argument. > + * > * Returns the count of returned statistics structures on success, -1 > on error. > * The requested data are returned in the @retStats parameter. The > returned > * array should be freed by the caller. See virDomainStatsRecordListFree. > @@ -11386,6 +11390,10 @@ virConnectGetAllDomainStats(virConnectPtr conn, > * Note that any of the domain list filtering flags in @flags may be > rejected > * by this function. > * > + * Note that this API is prone to exceeding maximum RPC if querying > too many VMs > + * with lots of statistics. It's suggested to query in batches of > 10VMs, which > + * should be good enough for VMs with 3000 disks + networks. > + * Coming to think about it... Why don't we just batch this ourselves under the hood and just return the merged result?