napkin-math
shim
napkin-math | shim | |
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13 | 2 | |
3,093 | 59 | |
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6.3 | 4.4 | |
12 days ago | 4 months ago | |
Rust | Python | |
MIT License | - |
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napkin-math
- capacity planning in system design interviews
- Napkin Math
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S3 Express Is All You Need
Most production storage systems/databases built on top of S3 spend a significant amount of effort building an SSD/memory caching tier to make them performant enough for production (e.g. on top of RocksDB). But it's not easy to keep it in sync with blob...
Even with the cache, the cold query latency lower-bound to S3 is subject to ~50ms roundtrips [0]. To build a performant system, you have to tightly control roundtrips. S3 Express changes that equation dramatically, as S3 Express approaches HDD random read speeds (single-digit ms), so we can build production systems that don't need an SSD cache—just the zero-copy, deserialized in-memory cache.
Many systems will probably continue to have an SSD cache (~100 us random reads), but now MVPs can be built without it, and cold query latency goes down dramatically. That's a big deal
We're currently building a vector database on top of object storage, so this is extremely timely for us... I hope GCS ships this ASAP. [1]
[0]: https://github.com/sirupsen/napkin-math
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Random Read or Sequential Read
Trying to estimate performance using some napkin math based on this: https://github.com/sirupsen/napkin-math
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A CVE has been issued for hyper. Denial of Service possible
So napkin maths time. Typical cross-world bog-standard network speeds for a single TCP channel of ~25MiBps. A single HEADERS+RST pair is likely < 128 bytes (40 for the HEADERS + whatever payload, and 32 for the RST). So 8 pairs per K, 8K pairs per MiB, 200K pairs per 25MiB...
- Index Merges vs Composite Indexes in Postgres and MySQL
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I/O is no longer the bottleneck
Yes, sequential I/O bandwidth is closing the gap to memory. [1] The I/O pattern to watch out for, and the biggest reason why e.g. databases do careful caching to memory, is that _random_ I/O is still dreadfully slow. I/O bandwidth is brilliant, but latency is still disappointing compared to memory.
[1]: https://github.com/sirupsen/napkin-math
- Monthly cost to host server for 1M DAUs?
- Napkin-math: Techniques and numbers for estimating system's performance
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System Design prep?
https://github.com/sirupsen/napkin-math (memorize these)
shim
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S3 Express Is All You Need
That's exactly how Userify[0] used to work. (when it was Python; now that it's a Go app, we do the caching in memory using Ristretto[1]).
0. https://userify.com (team ssh key management/sudo authz)
1. https://github.com/dgraph-io/ristretto
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Userify SSH Key Manager
Userify centralizes management of your users' SSH authorized_keys files across different projects and instance/server groups across multiple clouds. Using a web-interface (red=root, green=user, white=none), you can click to change permissions or remove access for that user across all servers in that group.
Your servers run a small (https://github.com/userify/shim) python script that continuously checks in with Userify via HTTPS. If a user no longer exists in that group, all sessions are actively killed (kill -9), the user account is deleted, and the home directory is renamed to /home/deleted:username so you can review the files in there at your convenience. If a user is later restored, that directory is automatically restored as well.
It's available via zero-install Userify Cloud or you can install your own server for data sovereignty.
What are some alternatives?
huniq - Filter out duplicates on the command line. Replacement for `sort | uniq` optimized for speed (10x faster) when sorting is not needed.
PyKMIP - A Python implementation of the KMIP specification.
advisory-database - Security vulnerability database inclusive of CVEs and GitHub originated security advisories from the world of open source software.
stormssh - Manage your SSH like a boss.
adix - An Adaptive Index Library for Nim
kms - A feature-rich, scalable, Key Management System
h2 - HTTP 2.0 client & server implementation for Rust.
EasyPGPeasy - It's an easy, simple and straightforward tool to create PGP Keypairs, import third-party (or your already created...) Keys and use them easily.
RAMCloud - **No Longer Maintained** Official RAMCloud repo
cowrie - Cowrie SSH/Telnet Honeypot https://cowrie.readthedocs.io
simdjson - Parsing gigabytes of JSON per second : used by Facebook/Meta Velox, the Node.js runtime, ClickHouse, WatermelonDB, Apache Doris, Milvus, StarRocks
BorgBackup - Deduplicating archiver with compression and authenticated encryption.