b690450e84
1. Background. Since the dawn of times mount-utils package tries to work around the bug in the Linux kernel, which results in occasional incomplete read of mountinfo entries (from either /proc/mounts or /proc/PID/mountinfo). The workaround used is to read the whole file twice and compare the two blobs. If they differ, try again. The kernel bug is manifesting when mountinfo read is performed concurrently with an unmount, and can easily be reproduced by running lots of mounts and unmounts in parallel with the code reading mountinfo. For one such reproducer, see https://github.com/kolyshkin/procfs-test. On a Kubernetes node with lots of short-lived containers, mounts and unmounts are quite frequent. This leads to the occasional bug, and surely results in much more re-reads of mountinfo, because the workaround assumes its content is more-or-less static. The good news is, this bug was finally fixed by kernel commit 9f6c61f96f2d97, which made its way into Linux 5.8. 2. The issue. The code still read every file at least twice, and up to 10 times. The chance of re-reading is higher if there is a mount or unmount going on at the same time. The result is higher system and kernel load, and degraded performance. 3. The fix. As the re-reading is not necessary for newer kernels, let's check the kernel version and skip the workaround if running Linux >= 5.8. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> |
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Kubernetes (K8s)
Kubernetes, also known as K8s, is an open source system for managing containerized applications across multiple hosts. It provides basic mechanisms for the deployment, maintenance, and scaling of applications.
Kubernetes builds upon a decade and a half of experience at Google running production workloads at scale using a system called Borg, combined with best-of-breed ideas and practices from the community.
Kubernetes is hosted by the Cloud Native Computing Foundation (CNCF). If your company wants to help shape the evolution of technologies that are container-packaged, dynamically scheduled, and microservices-oriented, consider joining the CNCF. For details about who's involved and how Kubernetes plays a role, read the CNCF announcement.
To start using K8s
See our documentation on kubernetes.io.
Take a free course on Scalable Microservices with Kubernetes.
To use Kubernetes code as a library in other applications, see the list of published components.
Use of the k8s.io/kubernetes module or k8s.io/kubernetes/... packages as libraries is not supported.
To start developing K8s
The community repository hosts all information about building Kubernetes from source, how to contribute code and documentation, who to contact about what, etc.
If you want to build Kubernetes right away there are two options:
You have a working Go environment.
mkdir -p $GOPATH/src/k8s.io
cd $GOPATH/src/k8s.io
git clone https://github.com/kubernetes/kubernetes
cd kubernetes
make
You have a working Docker environment.
git clone https://github.com/kubernetes/kubernetes
cd kubernetes
make quick-release
For the full story, head over to the developer's documentation.
Support
If you need support, start with the troubleshooting guide, and work your way through the process that we've outlined.
That said, if you have questions, reach out to us one way or another.
Community Meetings
The Calendar has the list of all the meetings in the Kubernetes community in a single location.
Adopters
The User Case Studies website has real-world use cases of organizations across industries that are deploying/migrating to Kubernetes.
Governance
Kubernetes project is governed by a framework of principles, values, policies and processes to help our community and constituents towards our shared goals.
The Kubernetes Community is the launching point for learning about how we organize ourselves.
The Kubernetes Steering community repo is used by the Kubernetes Steering Committee, which oversees governance of the Kubernetes project.
Roadmap
The Kubernetes Enhancements repo provides information about Kubernetes releases, as well as feature tracking and backlogs.