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

rgreenjr

-- show running queries (pre 9.2)
SELECT procpid, age(clock_timestamp(), query_start), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(clock_timestamp(), query_start), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

acook

require 'io/console'

# Reads keypresses from the user including 2 and 3 escape character sequences.
def read_char
  STDIN.echo = false
  STDIN.raw!

  input = STDIN.getc.chr
  if input == "\e" then
    input << STDIN.read_nonblock(3) rescue nil

garybernhardt

It's a subscription-based screencast site, where I post a new five- to
ten-minute screencast every week. For this, people pay a nominal fee
around $3 per month, giving them access to the full archives and new
screencasts as they happen. The style would be similar to the
screencasts I've posted on my blog: just me and the computer, recorded
in one take, although with much practicing. I'd focus not on new
languages and tools, but on the minute-to-minute mechanics of
effective programming practices, with an obvious bias toward the stack
and practices that I use.

Hupotronic

VP8 vs H.264 - Which One is Better?

So I was reading Hacker News and decided to read the comments in the thread about H.265 being approved. Pretty close to the top was this comment about VP9, Google's future video format. I have some words of my own about it and other future formats at the bottom of this post, but what jumped out from the comment to me was this part:

Many have already implemented VP8 (which is also slightly better than h.264 at this point)

The comparison linked to back up that statement is faulty for several reasons, such as not providing the source material used (hell, he doesn't even name the source material), exact encoding settings used (no, some random profiles are not enough), not providing the resulting encodes, only providing a

mislav

I use tmux splits (panes). Inside one of these panes there's a Vim process, and it has its own splits (windows).

In Vim I have key bindings C-h/j/k/l set to switch windows in the given direction. (Vim default mappings for windows switching are the same, but prefixed with C-W.) I'd like to use the same keystrokes for switching tmux panes.

An extra goal that I've solved with a dirty hack is to toggle between last active panes with C-\.

Here's how it should work:

mikedamage

#!/usr/bin/env ruby
#
# = Email Ping
#
# Check to see if an email address exists by looking up MX records and connecting
# to the address's home SMTP server. It then starts to send a message to the address
# but quits before the message is actually sent.

require 'resolv'
require 'net/smtp'

jasonrudolph

5 entertaining things you can find with the GitHub Search API

Let's have some command-line fun with curl, [jq][1], and the [new GitHub Search API][2].

Today we're looking for:

• The hottest repositories created in the last week.
• The oldest user accounts with zero followers. (So sad.)
• Issue trends by language.
• Clojure projects defying convention.

igrigorik

alias gh="open \`git remote -v | grep [email protected] | grep fetch | head -1 | cut -f2 | cut -d' ' -f1 | sed -e's/:/\//' -e 's/git@/http:\/\//'\`"

jpsim

1. Plain Strings (207): foo
2. Anchors (208): k$
3. Ranges (202): ^[a-f]*$
4. Backrefs (201): (...).*\1
5. Abba (169): ^(.(?!(ll|ss|mm|rr|tt|ff|cc|bb)))*$|^n|ef
6. A man, a plan (177): ^(.)[^p].*\1$
7. Prime (286): ^(?!(..+)\1+$)
8. Four (199): (.)(.\1){3}
9. Order (198): ^[^o].....?$
10. Triples (507): (^39|^44)|(^([0369]|([147][0369]*[258])|(([258]|[147][0369]*[147])([0369]*|[258][0369]*[147])([147]|[258][0369]*[258])))*$)