vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

chitchcock

Stevey's Google Platforms Rant

I was at Amazon for about six and a half years, and now I've been at Google for that long. One thing that struck me immediately about the two companies -- an impression that has been reinforced almost daily -- is that Amazon does everything wrong, and Google does everything right. Sure, it's a sweeping generalization, but a surprisingly accurate one. It's pretty crazy. There are probably a hundred or even two hundred different ways you can compare the two companies, and Google is superior in all but three of them, if I recall correctly. I actually did a spreadsheet at one point but Legal wouldn't let me show it to anyone, even though recruiting loved it.

I mean, just to give you a very brief taste: Amazon's recruiting process is fundamentally flawed by having teams hire for themselves, so their hiring bar is incredibly inconsistent across teams, despite various efforts they've made to level it out. And their operations are a mess; they don't real

zatarra

#!/usr/bin/python
import serial
import sys

latestByte  = ('c')
lastByte    = ('c')
inPacket    = False
myPacket    = []
PLENGTH     = 0

lukaslundgren

sudo apt-get install build-essential libsqlite3-dev zlib1g-dev libncurses5-dev libgdbm-dev libbz2-dev libreadline5-dev libssl-dev libdb-dev

wget http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz
tar -xzf Python-2.7.3.tgz
cd Python-2.7.3

./configure --prefix=/usr --enable-shared
make
sudo make install
cd ..

justinvanwinkle

# I was looking for a rate limiting library to call rate limited apis as closely 
#   as possible to their enforced limits.  I looked at the first few python libraries
#   that I found, and when I glanced at the source, they were all clearly broken.
# Curious how this could be, I took all the top google and pip search results for: python rate limiting
#   and tried to get them to do the wrong thing and fail to rate limit in situations that could come up 
#   in normal use (though in some cases very specific use)


# https://github.com/tomasbasham/ratelimit
# Where broken:

debasishg

General Background and Overview

1. Probabilistic Data Structures for Web Analytics and Data Mining : A great overview of the space of probabilistic data structures and how they are used in approximation algorithm implementation.
2. Models and Issues in Data Stream Systems
3. Philippe Flajolet’s contribution to streaming algorithms : A presentation by Jérémie Lumbroso that visits some of the hostorical perspectives and how it all began with Flajolet
4. Approximate Frequency Counts over Data Streams by Gurmeet Singh Manku & Rajeev Motwani : One of the early papers on the subject.
5. [Methods for Finding Frequent Items in Data Streams](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.9800&rep=rep1&t

mbostock

license: gpl-3.0
height: 960
redirect: https://observablehq.com/@d3/d3-zoomable-circle-packing

kurtbrose

from sqlalchemy import select, text


def reset_sequences(engine, schema="public", gap=10000):
    """
    Reset all sequences in a given schema to 10000, 20000, etc. so that ids won't overlap easily.
    Ensures we don't get "lucky" and crossing ids between tables works because they are both id=1,
    passing a test that should fail.
    """
    with engine.connect() as conn:

sebmarkbage

I heard some points of criticism to how React deals with reactivity and it's focus on "purity". It's interesting because there are really two approaches evolving. There's a mutable + change tracking approach and there's an immutability + referential equality testing approach. It's difficult to mix and match them when you build new features on top. So that's why React has been pushing a bit harder on immutability lately to be able to build on top of it. Both have various tradeoffs but others are doing good research in other areas, so we've decided to focus on this direction and see where it leads us.

I did want to address a few points that I didn't see get enough consideration around the tradeoffs. So here's a small brain dump.

"Compiled output results in smaller apps" - E.g. Svelte apps start smaller but the compiler output is 3-4x larger per component than the equivalent VDOM approach. This is mostly due to the code that is usually shared in the VDOM "VM" needs to be inlined into each component. The tr