Public bug reported:
a) nova compute service updates info of compute-node by run
update_available_resource every CONF.update_resources_interval(60s by default).
b) for every scheduler request:
1. select_destinations is called and get all HostStates(if compute-node is
newer that local hoststate info based on updated_at, update the HostStates with
the compute info from DB)
2. check if the host resource can meet instance requirement one by one with
updating the HostState resource iteratively, if yes, send
build_and_run_instance cast RPC to the corresponding compute node.
3.compute service accept the amqp message and consumed the instance requirement
and write new compute info into DB.
4.compute try to spawn the instance, once failed, roll back step 3.
My question:
if user set CONF.update_resources_interval 1s, that is, compute node service
updates compute info into DB every 1s.
For the case: the user sends multi nova boot request, and the first boot
request goes to step 2 and the compute node service runs periodic task
update_available_resource at the same time. And the second boot request go to
step 1 and the first request still not goes to step3, so the second boot
request gets HostStates set without the first instance's consumption and
scheduler service will schedule a host for it without considering the first
instance consumption. And the following request repeats.
Can this race condition occur?
** Affects: nova
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1488986
Title:
nova scheduler for race condition
Status in OpenStack Compute (nova):
New
Bug description:
a) nova compute service updates info of compute-node by run
update_available_resource every CONF.update_resources_interval(60s by default).
b) for every scheduler request:
1. select_destinations is called and get all HostStates(if compute-node is
newer that local hoststate info based on updated_at, update the HostStates with
the compute info from DB)
2. check if the host resource can meet instance requirement one by one with
updating the HostState resource iteratively, if yes, send
build_and_run_instance cast RPC to the corresponding compute node.
3.compute service accept the amqp message and consumed the instance
requirement and write new compute info into DB.
4.compute try to spawn the instance, once failed, roll back step 3.
My question:
if user set CONF.update_resources_interval 1s, that is, compute node service
updates compute info into DB every 1s.
For the case: the user sends multi nova boot request, and the first boot
request goes to step 2 and the compute node service runs periodic task
update_available_resource at the same time. And the second boot request go to
step 1 and the first request still not goes to step3, so the second boot
request gets HostStates set without the first instance's consumption and
scheduler service will schedule a host for it without considering the first
instance consumption. And the following request repeats.
Can this race condition occur?
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