---
features:
  - |
    Utilizing recent changes in oslo.messaging, the
    `rpc_response_timeout` value can now be increased significantly if
    needed or desired to solve issues with long-running RPC calls
    timing out before completing due to legitimate reasons (such as
    live migration prep). If `rpc_response_timeout` is increased
    beyond the default, nova will request active call monitoring from
    oslo.messaging, which will effectively heartbeat running
    activities to avoid a timeout, while still detecting failures
    related to service outages or message bus congestion in a
    reasonable amount of time. Further, the
    `[DEFAULT]/long_rpc_timeout` option has been added which allows
    setting an alternate timeout value for longer-running RPC calls
    which are known to take a long time. The default for this is 1800
    seconds, and the `rpc_response_timeout` value will be used for the
    heartbeat frequency interval, providing a similar
    failure-detection experience for these calls despite the longer
    overall timeout. Currently, only the live migration RPC call uses
    this longer timeout value.