| Posted | Nick | Remark | |
|---|---|---|---|
| #openstack-nova - 2017-07-31 | |||
| 15:04:46 | gibi_ | but after that PUT placement still has the old allocation as well | |
| 15:05:47 | gibi_ | does PUT /placement/allocations expected to totally overwrite the db for the instance | |
| 15:05:50 | gibi_ | ? | |
| 15:06:04 | melwitt | dansmith, mriedem: I have a fix up for a volume detach data corruption bug at https://review.openstack.org/#/c/488545/ that was caused by an earlier attempt to fix a different bug. has to be backported all the way to newton I think | |
| 15:06:05 | mriedem | yes | |
| 15:06:07 | mriedem | gibi_: yes | |
| 15:06:49 | mriedem | melwitt: good lord | |
| 15:07:05 | mriedem | i don't think the backports to newton ever landed because i also depended on them for another series | |
| 15:07:23 | melwitt | o rly | |
| 15:07:33 | mriedem | oh nvm https://review.openstack.org/#/c/425114/ | |
| 15:07:38 | mriedem | must be something else then | |
| 15:07:56 | cdent | gibi_: is there yet another PUT after the stripped one? | |
| 15:07:59 | mriedem | i was thinking of this series i have in newton https://review.openstack.org/#/c/470347/ | |
| 15:08:05 | mriedem | to wait for an interface to be detached | |
| 15:08:15 | melwitt | oh, okay | |
| 15:08:39 | cdent | gibi_: or is maybe the one with the stripped not being accepted (because of 409)? | |
| 15:09:57 | gibi_ | cdent: look at line 5-7 in http://paste.openstack.org/show/617028/ | |
| 15:10:07 | cdent | yeah, I'm there now | |
| 15:10:07 | gibi_ | cdent: sorry 4-7 | |
| 15:10:19 | gibi_ | cdent: 4 sends an allocation list with one item | |
| 15:10:52 | gibi_ | but line 6 writes two allocations to the db | |
| 15:12:01 | gibi_ | cdent: not two, three actually | |
| 15:12:12 | mriedem | melwitt: i think i was thinking of this https://review.openstack.org/#/c/441204/ | |
| 15:12:16 | mriedem | which is part of that newton series | |
| 15:12:20 | mriedem | and sounds similar to what you're doing | |
| 15:12:22 | gibi_ | cdent: but all for the same provider so this is not the problem | |
| 15:13:10 | cdent | gibi_: right, what you are seeing there is just an artifact of the object: an REST-level allocation is made up of multiple Allocation Objects | |
| 15:13:31 | gibi_ | cdent: yeah, I see now. sorry | |
| 15:13:41 | melwitt | mriedem: oh, right. I noticed that too at some point thinking it's related but it seems like it's not, i.e. in the case of the bug I think isPersistent() will still return True | |
| 15:13:42 | gibi_ | cdent: anyhow there is no other PUT on allocations later in the log | |
| 15:13:53 | cdent | yeah, | |
| 15:14:52 | melwitt | mriedem: the domain will still be persistent even if the volume had been detached from the persistent config in the past | |
| 15:15:01 | cdent | gibi_: line 148 is demonstrating how things are wrong, correct? that's after confirm, and some time to let things settled? | |
| 15:15:38 | cdent | so source hasn't cleaned up | |
| 15:16:09 | gibi_ | cdent: yes | |
| 15:17:49 | cdent | gibi_: so the problem is somewhere near here: https://review.openstack.org/#/c/488510/4/nova/compute/resource_tracker.py@1083 | |
| 15:18:16 | cdent | sorry, not there | |
| 15:18:36 | cdent | 476 | |
| 15:19:33 | gibi_ | but that is the piece of code that generates our PUT | |
| 15:19:40 | gibi_ | and that PUT seems correct | |
| 15:19:40 | gibi_ | to me | |
| 15:19:45 | cdent | true | |
| 15:26:47 | gibi_ | I added code to https://review.openstack.org/#/c/488510/4/nova/scheduler/client/report.py@1079 to read back the allocations the code just PUT-ed | |
| 15:26:54 | gibi_ | http://paste.openstack.org/show/617031/ | |
| 15:27:15 | gibi_ | and the GET returns both allocations after the PUT | |
| 15:27:31 | gibi_ | so the problem is in the placement I think | |
| 15:28:04 | cdent | wow | |
| 15:28:15 | cdent | that will be an exciting bug if so | |
| 15:28:46 | dansmith | I'm missing the obvious thing | |
| 15:29:00 | cdent | gibi_: yeah | |
| 15:29:03 | dansmith | oh, we can't read back the allocations we just wrote in a particular place? | |
| 15:29:17 | cdent | it only deletes where rp uuid and consume uuid == | |
| 15:29:21 | cdent | not just consumer uuid | |
| 15:29:47 | bauzas | interesting | |
| 15:30:16 | cdent | https://github.com/openstack/nova/blob/master/nova/objects/resource_provider.py#L1509-L1520 | |
| 15:30:43 | cdent | gibi_: see what happens if you get rid of the first == in the and_ | |
| 15:30:52 | gibi_ | checking | |
| 15:31:01 | bauzas | yeah that will work | |
| 15:31:09 | bauzas | obviously | |
| 15:31:17 | cdent | dansmith: we had in our brains that we were removing all allocations for the consumer | |
| 15:31:24 | cdent | but the code is only removing some of them | |
| 15:32:33 | dansmith | meaning, the api is such that all should be removed, but some bug in the db side of placement prevents that from happening? | |
| 15:32:50 | cdent | yeah | |
| 15:32:59 | dansmith | that seems ungood | |
| 15:33:15 | cdent | it looks like the original goal was to _only_ remove exact matches (not sure why) | |
| 15:33:22 | cdent | (the comment says as much) | |
| 15:33:27 | dansmith | hmm | |
| 15:33:41 | dansmith | jaypipes seemed to think that should be fully atomic, so that seems weird | |
| 15:33:59 | gibi_ | I can confirm that removing the rp == from the db code makes the placement API behave as expected in this particular case http://paste.openstack.org/show/617034/ | |
| 15:34:16 | cdent | and we had three authors on that particular change, so is probably going to be hard to remember the whys and wherefores | |
| 15:34:18 | cdent | gibi_: nice | |
| 15:34:56 | cdent | dansmith: since we've been assuming all this time that the behavior is one thing and not the other, I think we should just change it | |
| 15:35:12 | cdent | also I don't think there is much risk, because we haven't been doing any dual provider allocations up til now | |
| 15:35:39 | cdent | edleafe: you listening ^ ? | |
| 15:35:42 | cdent | brb | |
| 15:36:19 | gibi_ | I'll let you guys to report a bug and propose a fix as my workday is over soon. | |
| 15:36:46 | cdent | gibi_: right on, thanks very much for all your digging | |
| 15:37:16 | jaypipes | rock on, thanks gibi | |
| 15:37:25 | dansmith | cdent: right, and I think that's the thing the api espouses anyway | |
| 15:38:10 | edleafe | cdent: sorry, distracted by meeting. Trying to follow, though | |
| 15:38:29 | jaypipes | dansmith, cdent: so shall I remove that == rp_uuid line in a separate patch or in the same confirm_resize() patch? | |
| 15:38:33 | cdent | edleafe: no worries, just wanted your memory if anything | |
| 15:38:39 | dansmith | jaypipes: definitely separate | |
| 15:38:49 | dansmith | jaypipes: we probably need to backport that right? | |
| 15:38:51 | jaypipes | dansmith: ahead of confirm_resize() yeah? | |
| 15:38:55 | dansmith | yeah | |
| 15:38:55 | jaypipes | dansmith: ya | |
| 15:39:00 | jaypipes | ok, I'm on it. | |
| 15:39:35 | bauzas | jaypipes: if we remove the == rp, wouldn't that be a problem for racy calls ? | |
| 15:39:55 | jaypipes | bauzas: no | |
| 15:39:57 | bauzas | jaypipes: because previously we were just supposing the generation bit to be updated | |
| 15:40:06 | bauzas | given that generation is per RP | |
| 15:40:18 | jaypipes | bauzas: the generation is on the RP. this code is removing allocation records. | |
| 15:40:43 | jaypipes | bauzas: this is leftover code that was assuming a single RP for an allocation | |
| 15:41:14 | jaypipes | 1509gg | |
| 15:41:17 | jaypipes | ffs | |
| 15:43:02 | cdent | the bug: https://bugs.launchpad.net/nova/+bug/1707669 | |
| 15:43:04 | openstack | Launchpad bug 1707669 in OpenStack Compute (nova) "[placement] put allocations does not do a full overwrite of existing allocations" [High,Triaged] | |
| 15:44:34 | jaypipes | cdent: danke | |
| 15:50:59 | sdague | 2 easy bugs to close - https://review.openstack.org/#/c/486642/ | |