Balazs Gibizer
f16170695c
During the VM hard reboot there is 3 events coming from libvirt * STOPPED * RESUMED * STARTED The libvirt driver implements automatic power sync of the VM based on the STOPPED event. But it should not do a stop() compute api call if the STOPPED event is followed right after by a STARTED event during hard reboot. So the libvirt driver delays processing the STOPPED event by 15 seconds and cancels the event if another lifecycle event is received for the same domain during that delay. In eventlet mode this is implemented by sheduling a greenlet and cancelling it. With native threading we cannot cancel a running task / thread so we need a bit smarter solution than just adding a sleep to the event handler and putting it in a threadpool. So this patch introduces an Executor wrapper that allows delaying the submission of a task into a real Executor by a predefine delay and checks for cancellation before during the real submission. The wrapper uses a single thread and a queue of tasks. As the delay is the same for every tasks the ordering of the execution of the tasks are the same as the order they was submitted to the wrapper. So the thread can process the queue of tasks one by one, check for the remaining time until the deadline of the oldest task then submit it to the real executor, then take the next task from the queue. Cancellation of a task is checked before any wait for a deadline and before the submission to the real executor. So a task is never executed if cancelled during its delay period. Change-Id: I8fb3bb1e5506f2792522bf822939e7e8ab68763d Signed-off-by: Balazs Gibizer <gibi@redhat.com>
============== OpenStack Nova ============== OpenStack Nova provides a cloud computing fabric controller, supporting a wide variety of compute technologies, including: libvirt (KVM, Xen, LXC and more), VMware and OpenStack Ironic. Use the following resources to learn more. API --- To learn how to use Nova's API, consult the documentation available online at: - `Compute API Guide <https://docs.openstack.org/api-guide/compute/>`__ - `Compute API Reference <https://docs.openstack.org/api-ref/compute/>`__ For more information on OpenStack APIs, SDKs and CLIs in general, refer to: - `OpenStack for App Developers <https://www.openstack.org/appdev/>`__ - `Development resources for OpenStack clouds <https://developer.openstack.org/>`__ Operators --------- To learn how to deploy and configure OpenStack Nova, consult the documentation available online at: - `OpenStack Nova <https://docs.openstack.org/nova/>`__ In the unfortunate event that bugs are discovered, they should be reported to the appropriate bug tracker. If you obtained the software from a 3rd party operating system vendor, it is often wise to use their own bug tracker for reporting problems. In all other cases use the master OpenStack bug tracker, available at: - `Bug Tracker <https://bugs.launchpad.net/nova>`__ Developers ---------- For information on how to contribute to Nova, please see the contents of the CONTRIBUTING.rst. Any new code must follow the development guidelines detailed in the HACKING.rst file, and pass all unit tests. To understand better the processes that the team is using, please refer to the `Process document <https://docs.openstack.org/nova/latest/contributor/process.html>`__. Further developer focused documentation is available at: - `Official Nova Documentation <https://docs.openstack.org/nova/>`__ - `Official Client Documentation <https://docs.openstack.org/python-novaclient/>`__ Other Information ----------------- During each `Summit`_ and `Project Team Gathering`_, we agree on what the whole community wants to focus on for the upcoming release. The plans for nova can be found at: - `Nova Specs <http://specs.openstack.org/openstack/nova-specs/>`__ .. _Summit: https://www.openstack.org/summit/ .. _Project Team Gathering: https://www.openstack.org/ptg/