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#openstack-nova - 2018-02-16
20:55:38 fried_rice We're creating the RP in placement with compute_node.uuid, compute_node.hypervisor_hostname
20:56:00 TheJulia so they can never fail between compute nodes.... heh
20:56:09 fried_rice Under what circumstances could I get a compute_node with the same hypervisor_hostname but a *different* uuid?
20:56:32 TheJulia if a compute process went down too long and the hash ring recalculated
20:56:51 TheJulia the other compute process would take over for the other nodes
20:57:14 TheJulia or at least, that is what we were doing as i understand it
20:57:52 fried_rice Cool cool. But why doesn't the second compute process perceive the nodes as having the same UUID as the first compute process did?
20:58:30 TheJulia and now I'm confused :)
21:00:34 fried_rice TheJulia: resource_tracker.py in the 900s
21:00:41 fried_rice sorry, 500s
21:00:50 TheJulia thanks
21:01:06 fried_rice In particular, I thought I4253cffca3dbf558c875eed7e77711a31e9e3406 was supposed to be attacking this very problem.
21:06:22 fried_rice TheJulia: I think I get it. Is the hypervisor_hostname is assigned based on compute_node.host?
21:06:59 TheJulia that is what I think, it is just I've never dug through this portion of nova, so I'm not grasping it very well
21:07:24 TheJulia also *squirrel* *blink* *blink*
21:07:56 fried_rice mriedem: Executive summary on the difference between nodename and hypervisor_hostname?
21:08:55 jroll in ironic-land, nodename == ironic node uuid, hypervisor_hostname == nova-compute hostname (rabbit queue)
21:09:11 fried_rice Aha
21:09:15 fried_rice I think therein lies the boggle.
21:09:27 fried_rice Because in non-ironic-land, I *think* they are the same.
21:09:33 fried_rice And we're using the wrong one.
21:09:50 jroll the patch you mentioned was meant to handle this, but I think only for the compute_nodes table, not resource providers
21:10:58 jroll (emphasis on I think)
21:11:11 fried_rice L869
21:11:38 jroll nice.
21:12:05 mriedem for non-ironic, compute_nodes.host and compute_nodes.hypervisor_hostname are the same
21:13:14 jroll wait, 869 can't be wrong, we would have never had any resources
21:13:24 jroll that would have blown up all over the place
21:13:31 jroll did I have this backwards?
21:13:41 TheJulia hmmmmmmmm
21:15:46 jroll fried_rice: I'm sorry, I lied. hypervisor_hostname is the ironic node uuid
21:16:09 jroll compute_node.host is the nova-compute hostname
21:16:36 jroll your use of nodename threw me off, that is equivalent in (most? all?) places to hypervisor_hostname
21:17:10 fried_rice So then we go back to the original question: How does compute_node.uuid *change* when compute_node.hypervisor_hostname is the same?
21:18:09 jroll compute_node.uuid does not
21:18:14 jroll but resource provider uuid does
21:18:16 jroll afaict
21:18:40 fried_rice No, because the error is happening via _ensure_resource_provider(compute_node.uuid, compute_node.hypervisor_hostname)
21:18:46 fried_rice and we're running into a conflict on the latter.
21:19:32 jroll is resource provider UUID always the same as compute node uuid?
21:19:51 fried_rice For compute node resource providers, in Queens, yes.
21:19:56 fried_rice Uhm.
21:19:59 fried_rice Yes.
21:20:07 fried_rice Was gonna say get_inventory might be able to muck with it, but no.
21:20:19 fried_rice Is this because nova is creating the ComputeNode entries afresh, with an autogenerated UUID?
21:20:40 jroll seems like it would be, yes. but that's what https://review.openstack.org/#/c/508555/ should have fixed
21:20:57 fried_rice Exacitically
21:21:08 fried_rice L518-9 in fact
21:21:20 jroll right
21:23:02 jroll we demonstrate that code is running: http://logs.openstack.org/50/544750/10/check/ironic-grenade-dsvm-multinode-multitenant/d7a1ee7/logs/subnode-2/screen-n-cpu.txt.gz#_Feb_16_17_21_04_613786
21:24:05 fried_rice I'm sorta guessing you can't change the UUID of a ComputeNode in the db. mriedem?
21:24:14 jroll both compute nodes appear to be attempting to create an RP for that node (9de4d7b4-51c9-4088-99b4-cd648332504e), at different times of course
21:24:31 fried_rice Right; the first one succeeds but the second one barfs
21:24:33 fried_rice right?
21:24:34 jroll um
21:24:43 jroll well, both fail
21:24:48 mriedem fried_rice: changing the uuid would be kinda bad
21:24:52 jroll but my um: how do we feel about adding a cn.save() here: https://github.com/openstack/nova/blob/master/nova/compute/resource_tracker.py?utf8=%E2%9C%93#L525
21:25:11 fried_rice jroll: I was going to suggest that.
21:25:20 fried_rice but also not knowing if it's The Right Thing.
21:25:28 fried_rice I was also going to suggest setting the UUID before save()ing.
21:25:35 fried_rice But mriedem won't come to my birthday party if I do that.
21:25:51 jroll nah, the UUID should be fine, we're updating an existing CN
21:26:21 fried_rice But I thought that was the whole problem.
21:26:46 fried_rice btw, assuming _resource_change returns True, that .save() should be getting done at L859.
21:27:28 jroll yeah, I'm not sure it will, the schedulable resources should be the same as before, only the host attribute is changing
21:30:14 jroll ok, I get it now, we did get a new UUID, wtf
21:30:29 fried_rice w, indeed, tf
21:30:47 jroll sorry, I got confuzzled
21:31:40 jroll you know...
21:32:04 jroll does a compute_node record get deleted at some point if the compute service disappears?
21:32:13 jroll and if so, do we clean up the resource providers?
21:33:09 fried_rice I could answer that second question if I knew the answer to the first. But I don't. mriedem? (Or mriedem if you'd care to delegate, who's around who knows this stuff?)
21:33:36 jroll so um
21:33:43 jroll this is pike->queens, afaik
21:33:53 jroll can we please land https://review.openstack.org/#/c/527423/ .
21:33:56 openstackgerrit Eric Fried proposed openstack/nova master: WIP: Make sure rebalance saves the compute node https://review.openstack.org/545464
21:34:07 fried_rice jroll: Here's a quickie to make sure that save() is happening ^
21:34:40 fried_rice jroll: But where the error happens, we're clearly running that code.
21:34:45 jroll er, the one I'm looking at is queens->master
21:34:47 jroll yeah
21:35:01 fried_rice So whereas I agree we should land that backport, that's not gonna be your fix here.
21:35:15 mriedem jroll: it doesn't
21:35:20 jroll sorry, we've been having issues with this job since before queens was cut, so I've been getting confused
21:35:23 mriedem compute_nodes hang out until manually removed
21:35:29 jroll damn
21:35:56 mriedem there are some bugs that tssurya opened for removing compute nodes and providers
21:36:14 jroll I was hoping compute nodes did get deleted but not RPs
21:36:18 jroll that would explain things
21:36:26 openstack Launchpad bug 1749734 in OpenStack Compute (nova) "Purge the compute_node records, resource provider records and host_mappings when doing force delete of the host" [Medium,Confirmed] - Assigned to Surya Seetharaman (tssurya)
21:36:26 mriedem https://bugs.launchpad.net/nova/+bug/1749734
21:36:30 jroll thanks
21:37:26 fried_rice jroll: I can get a little more aggressive with the hacking.
21:38:27 jroll fried_rice: feel free, I'm just trying to wrap my head around some of this
21:38:48 jroll this seems wrong. http://logs.openstack.org/50/544750/10/check/ironic-grenade-dsvm-multinode-multitenant/d7a1ee7/logs/screen-n-cpu.txt.gz#_Feb_16_17_06_33_592313
21:39:09 jroll oh, there we are http://logs.openstack.org/50/544750/10/check/ironic-grenade-dsvm-multinode-multitenant/d7a1ee7/logs/screen-n-cpu.txt.gz#_Feb_16_17_04_22_814020
21:39:35 jroll but we can't talk to placement, so the RP stays
21:39:57 jroll because Feb 16 17:04:22.591129 ubuntu-xenial-rax-ord-0002580076 nova-compute[28778]: DEBUG nova.virt.ironic.driver [None req-969cdb75-026b-4cac-ba09-3f3be962a09d service nova] Returning 0 available node(s) {{(pid=28778) get_available_nodes /opt/stack/old/nova/nova/virt/ironic/driver.py:757}}
21:40:01 jroll because ironic is down
21:40:05 jroll got dang.

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