RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Description of problem:
libvirt has many APIs to query the statistics of a domain, for example virDomainGetInfo, virDomainBlockInfo.

All these API are synchronous. Thus, a client application, like VDSM, needs to spawn a thread per Domain/VM in order to run all the queries.

This leads to waste of resources like the one found in https://bugzilla.redhat.com/show_bug.cgi?id=1102147#c54

We need a way to do async queries in order to reduce the number of active threads. This is to save resources, not for performance.

Affected APIs as in vdsm 4.15 / oVirt 3.5.0:

virDomainBlockInfo
virDomainGetInfo
virDomainGetCPUStats
virDomainBlockStats
virDomainBlockStatsFlags
virDomainInterfaceStats
virDomainGetVcpusFlags
virDomainGetMetadata

and their python counterpart

from the list on https://bugzilla.redhat.com/show_bug.cgi?id=1113106#c1

virDomainGetMetadata can be elided once https://bugzilla.redhat.com/show_bug.cgi?id=1114492 is fixed

For now it looks like the normal bulk stats API is sufficient. If it proves necessary to provide the async one please reopen this BZ.