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Thanks for the good explanation, was just a curiosity of mine.

Any idea why it has taken so long for the eventlet folks to fix this (I know u proposed a patch/patches a while ago)? Is eventlet really that unmaintained? :(

From: Chris Behrens <cbehrens at codestud.com<mailto:cbehrens at codestud.com>>
Date: Thursday, April 17, 2014 at 4:59 PM
To: Joshua Harlow <harlowja at yahoo-inc.com<mailto:harlowja at yahoo-inc.com>>
Cc: Chris Behrens <cbehrens at codestud.com<mailto:cbehrens at codestud.com>>, "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: Re: [openstack-dev] oslo removal of use_tpool conf option


On Apr 17, 2014, at 4:26 PM, Joshua Harlow <harlowja at yahoo-inc.com<mailto:harlowja at yahoo-inc.com>> wrote:

Just an honest question (no negativity intended I swear!).

If a configuration option exists and only works with a patched eventlet why is that option an option to begin with? (I understand the reason for the patch, don't get me wrong).


Right, it’s a valid question. This feature has existed one way or another in nova for quite a while. Initially the implementation in nova was wrong. I did not know that eventlet was also broken at the time, although I discovered it in the process of fixing nova’s code. I chose to leave the feature because it’s something that we absolutely need long term, unless you really want to live with DB calls blocking the whole process. I know I don’t. Unfortunately the bug in eventlet is out of our control. (I made an attempt at fixing it, but it’s not 100%. Eventlet folks currently have an alternative up that may or may not work… but certainly is not in a release yet.)  We have an outstanding bug on our side to track this, also.

The below is comparing apples/oranges for me.

- Chris


Most users would not be able to use such a configuration since they do not have this patched eventlet (I assume a newer version of eventlet someday in the future will have this patch integrated in it?) so although I understand the frustration around this I don't understand why it would be an option in the first place. An aside, if the only way to use this option is via a non-standard eventlet then how is this option tested in the community, aka outside of said company?

An example:

If yahoo has some patched kernel A that requires an XYZ config turned on in openstack and the only way to take advantage of kernel A is with XYZ config 'on', then it seems like that’s a yahoo only patch that is not testable and useable for others, even if patched kernel A is somewhere on github it's still imho not something that should be a option in the community (anyone can throw stuff up on github and then say I need XYZ config to use it).

To me non-standard patches that require XYZ config in openstack shouldn't be part of the standard openstack, no matter the company. If patch A is in the mainline kernel (or other mainline library), then sure it's fair game.

-Josh

From: Chris Behrens <cbehrens at codestud.com<mailto:cbehrens at codestud.com>>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Date: Thursday, April 17, 2014 at 3:20 PM
To: OpenStack Development Mailing List <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: [openstack-dev] oslo removal of use_tpool conf option


I’m going to try to not lose my cool here, but I’m extremely upset by this.

In December, oslo apparently removed the code for ‘use_tpool’ which allows you to run DB calls in Threads because it was ‘eventlet specific’. I noticed this when a review was posted to nova to add the option within nova itself:

https://review.openstack.org/#/c/59760/

I objected to this and asked (more demanded) for this to be added back into oslo. It was not. What I did not realize when I was reviewing this nova patch, was that nova had already synced oslo’s change. And now we’ve released Icehouse with a conf option missing that existed in Havana. Whatever projects were using oslo’s DB API code has had this option disappear (unless an alternative was merged). Maybe it’s only nova.. I don’t know.

Some sort of process broke down here.  nova uses oslo.  And oslo removed something nova uses without deprecating or merging an alternative into nova first. How I believe this should have worked:

1) All projects using oslo’s DB API code should have merged an alternative first.
2) Remove code from oslo.
3) Then sync oslo.

What do we do now? I guess we’ll have to back port the removed code into nova. I don’t know about other projects.

NOTE: Very few people are probably using this, because it doesn’t work without a patched eventlet. However, Rackspace happens to be one that does. And anyone waiting on a new eventlet to be released such that they could use this with Icehouse is currently out of luck.

- Chris



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