c0484c9d7c
When Linux runs out of memory and activates the OOM killer, it scores processes based on how much memory they are using[1]. If a job triggers an OOM by causing ansible-playbook to use a lot of RAM, normally we would expect the OOM killer to kill Ansible. However, if the executor is busy, it may be using a lot of RAM as well, and its score may exceed the score of the smaller Ansible process. Nonetheless, we would still rather kill the Ansible process. This adjusts the score for the bubblewrap and ansible processes so that they will have a score increased by an amount equal to about 20% of system RAM. This effectively means that as long as the executor uses less than 20% of system RAM, it is guaranteed to score lower than Ansible (and likely will continue to score lower for some significant amount over that as well, depending on how much RAM Ansible is using). We read the executor's oom_score_adj when we initialize the bwrap driver and add 200 to it in order to accomodate the situation where the executor has its own oom_score_adj. We always want the bwrap children to have a higher score than the executor. The choom program adjusts the OOM score for the command that it executes, and this is inherited by child processes. So we adjust bwrap and expect ansible-playbook to inherit it. It is also possible to adjust the score of the exeucotor process lower (so the executor could be made less likely to be a target) but that requires root privileges, so is not implemented in this change. [1] https://lxr.linux.no/#linux+v6.7.1/mm/oom_kill.c#L201 Change-Id: I3a3d116cf68b84b8a6f9ec13808d1d2c2008008f
Zuul
Zuul is a project gating system.
The latest documentation for Zuul v3 is published at: https://zuul-ci.org/docs/zuul/
If you are looking for the Edge routing service named Zuul that is related to Netflix, it can be found here: https://github.com/Netflix/zuul
If you are looking for the Javascript testing tool named Zuul, it can be found here: https://github.com/defunctzombie/zuul
Getting Help
There are two Zuul-related mailing lists:
- zuul-announce
-
A low-traffic announcement-only list to which every Zuul operator or power-user should subscribe.
- zuul-discuss
-
General discussion about Zuul, including questions about how to use it, and future development.
You will also find Zuul developers on Matrix <https://matrix.to/#/#zuul:opendev.org>.
Contributing
To browse the latest code, see: https://opendev.org/zuul/zuul To clone the latest code, use git clone https://opendev.org/zuul/zuul
Bugs are handled at: https://storyboard.openstack.org/#!/project/zuul/zuul
Suspected security vulnerabilities are most appreciated if first reported privately following any of the supported mechanisms described at https://zuul-ci.org/docs/zuul/user/vulnerabilities.html
Code reviews are handled by gerrit at https://review.opendev.org
After creating a Gerrit account, use git review to submit patches. Example:
# Do your commits
$ git review
# Enter your username if promptedJoin us on Matrix to discuss development or usage.
License
Zuul is free software. Most of Zuul is licensed under the Apache License, version 2.0. Some parts of Zuul are licensed under the General Public License, version 3.0. Please see the license headers at the tops of individual source files.
Python Version Support
Zuul requires Python 3. It does not support Python 2.
Since Zuul uses Ansible to drive CI jobs, Zuul can run tests anywhere Ansible can, including Python 2 environments.