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?

Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

dopey

package main

import (
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"io"
	"math/big"
)

tsaqib

Ideas

I have collected and moderated these ideas from various public sources and put into one place so that problem solvers and solution developers may find inspirations. Because I wish to update it regularly, I have setup as a single page wiki. You may try these ideas on hackathons/competitions/research; some are quite intense problems and some are not. Many of the problems were prepared keeping Dhaka/Bangladesh in mind, but of course can be applied to just about any underdeveloped/developing and sometimes developed countries.

Categories:

• Eradicate Extreme Poverty and Hunger
• Education
• Healthcare
• Governance

nhymxu

gunicorn run:app --workers=9
gunicorn run:app --workers=9 --worker-class=meinheld.gmeinheld.MeinheldWorker

Macbook Pro 2015 Python 3.7

Framework	Server	Req/s	Max latency	+/- Stdev

ursuad

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

metafeather

# ref: https://play.golang.org/p/OeEmT_CXyO
package main

import (
	"fmt"
	"runtime"
	"strconv"
	"strings"
	"sync"
)

kevin-lee

JProfiler with Docker

Docker

DockerFile

DockerFile should have JProfiler installation.

RUN wget <JProfiler file location> -P /tmp/ && \
  tar -xzf /tmp/<JProfiler file> -C /usr/local && \
  rm /tmp/<JProfiler file>

drorata

# Initialize the scroll
page = es.search(
  index = 'yourIndex',
  doc_type = 'yourType',
  scroll = '2m',
  search_type = 'scan',
  size = 1000,
  body = {
    # Your query's body
    })

ianfleeton

// Save this as MineSweeper.java
// compile with this command
// javac MineSweeper.java
// then run with this command
// java MineSweeper

// We need this for random numbers.
import java.util.Random;

class MineSweeper {