hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

jabley

#!/bin/sh

# script to automate the load and export to CSV of an oracle dump
# This script assumes:
# * you have the vagrant published key available locally in your .ssh directory
# * You have the Oracle VirtualBox image running locally
# ** ssh port-forwarding is configured for host port 2022 -> guess port 22.

set -e

mapmeld

OverEncrypt

This is a guide that I wrote to improve the default security of my website https://fortran.io , which has a certificate from LetsEncrypt. I'm choosing to improve HTTPS security and transparency without consideration for legacy browser support.

WARNING: if you mess up settings, lose your certificates, or decide to no longer maintain HTTPS certs, these steps can and will make your domain inaccessible.

I would recommend these steps only if you have a specific need for information security, privacy, and trust with your users, and/or maintain a separate secure.example.com domain which won't mess up your main site. If you've been thinking about hosting a site on Tor, then this might be a good option, too.

The best resources that I've found for explaining these steps are https://https.cio.gov , https://certificate-transparency.org , and https://twitter.com/konklone

djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

TimJDFletcher

Forward GnuPG agent from macOS to Linux

On the remote machine

Run gpg once as your to create the directory structure

gpg --list-keys

For headless systemd based hosts

a1994sc

---
apiVersion: apps/v1
#kind: Deployment
kind: DaemonSet
metadata:
  name: cloudflared
  namespace: ingress
  labels:
    group: cloudflare
spec: