You can for sure scale up. Otherwise, see below. Either give up consistency (1), or make writes slower (2), or use a version number (3). Or break the data down into smaller consistent chunks (4), which is usually not feasible. 1. Give up consistency and expose clients to stale writes.…
C++ std::move and Rust's move are different. std::move leaves behind the origin in a valid (but "undefined", whatever that is) state, usable and later to be deconstructed. Rust leaves the origin destroyed and unusable. If you try to use the origin after the move,…
How common libraries are doing it * Lookups: lock a segment of the hashtable instead of the entire thing. (concurrent_hash_map.h) * Inserts: lock the pending element (slot) of the target value, instead of the segment. (concurrent_hash_map.h) * Updates: RCU the element instead of locking it, allowing updates…
Recently I had the "pleasure" to work on something I've never worked on before. An organisation next door came asking for help. They wanted us to donate engineers helping them testing our code running in their binary. They were carrying out a huge architecture change, and…
I've been talking with a friend of mine about interview questions. One question keeps popping up: what are the ways that we could protect a service against excessive traffic? What we refer to as "a service", is a typical micro service that serves user requests. A…
RPC servers usually have several components: a thread pool (or green threads), local resources that are shared between requests (logging, metrics, throttling data, cache etc), and remote resources (databases and dependency systems). It is usually hard to cleanly shutdown a RPC server because the different types of resources involved. It…
When coding on ruaft [https://github.com/ditsing/ruaft] I adopted this "state transfer" style API to allow a graceful shutdown. To make the shutdown "safe" I insisted on taking the Raft instance away when the API is called, like the following. impl Raft { pub fn…
In this post, we'll explain how Raft handles read only requests. To those who are unfamiliar, Raft is an algorithm that replicates a shared state to a group of servers using leader election. Raft maintains a change log that is consistent among all replicas. The log is append-only.…