The AWS Firecracker paper is fascinating because Amazon has implemented a new Virtual Machine Monitor (VMM) which closely matches the requirements of their AWS Lambda service. While doing so, they carefully navigated the space of existing virtualization options, reused the best parts where they could, and implemented the rest. They also describe how they successfully rolled this out in production. I thought this paper provides a great example of the big technical possibilities open to large Cloud providers. This post is my simplified notes from that paper. …

Given that database transactions have been around for decades, I was surprised to find that some concepts and implementations still don’t have generally agreed-upon terminology, especially across vendors. And even the ANSI SQL standard’s description of Isolation Levels has been found to be lacking in places.

I made some notes recently about selected topics in database transactions for my own reference as I was reading through these parts. Beware that my simplifications may have subtle errors too! I have added a few good references at the end.

Isolation Levels

When transactions execute concurrently, they can interfere with each other when…

TiDB is an interesting new database, and PingCAP is the company driving most of its development. Recently I read the paper written about it, titled TiDB: A Raft based HTAP database, partly due to my interest in its Rust-based TiKV component. I found the paper to be comprehensive and well written. Below is my bullet points style summary of it.

Overview

• Ti = Titanium. HTAP = Hybrid Transactional and Analytical Processing
• A unified system that supports both Transactional Processing (TP) and Analytical Processing (AP) workloads, albeit with separate storage layers (TiKV, TiFlash). Having a single system simplifies development and ops.
• …

If you are familiar with Java or C/C++, understanding the assignment operator (=) in Rust will demystify a lot of its memory semantics. Assignment in Rust can have a range of outcomes depending on what you are assigning from and to, and on whether you are using the reference operator (&) and the mut keyword (short for mutable). In this post I will describe some scenarios of the assignment operation in Rust.

But first, two definitions:

1. When you instantiate an object and assign it to a variable, only that variable controls write access privileges to the memory region associated with…

This post describes the features k8s provides for Automated Scaling of applications. This is Part 3 of a series. Part 1 is an Introduction to K8S and Part 2 talks about Kubernetes Internals.

• k8s can automate horizontal scaling of pods and has experimental support for vertical scaling. Scaling can even extend to requesting new hardware nodes using the infra provider’s API. Scaling can be based on utilization of actual hardware (CPU/memory), or pod metrics like QPS across the pods, or cluster wide objects like load on a database or network.
• For horizontal scaling, the HorizontalPodAutoscaler (HPA) tracks current values of…

This post summarizes the internal architecture of Kubernetes (k8s). For my previous post on user-facing aspects, see Part 1 of the series.

• An architectural style that is followed throughout the control plane of k8s is of components communicating with each other using a data store (etcd) as the intermediary. Updates made to etcd are picked up by relevant observers and acted upon (see figure below).

• k8s has master and worker nodes.
• The master node manages the overall cluster and runs these processes: etcd, API server, Scheduler and a Controller Manager.
• Worker nodes execute the tasks, and they run: kubelet, kube-proxy…

I decided to start learning about Kubernetes (k8s) although I have not used it in production yet. These are my notes from the first part of the comprehensive book “Kubernetes in Action”. The second part gets into k8s’s internals. I will write about that as I read more of the book.

• k8s abstracts away the individual machine-level details of a cluster of machines. The cluster’s hardware capacity is available as a collection of “containers” for developers to deploy and scale their apps. For more on containers themselves, see my post: Docker — a conceptual overview.
• k8s also promises automatic restarts…

This is a crisp booklet by the famous management consultant Peter Drucker. It focuses on a few time tested general practices and hammers them home nicely rather than getting lost in the weeds — https://medium.com/pramod-biligiris-blog/book-review-the-effective-executive-854f69d04fd