nelsnelson

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             
Syscall on Intel 5150 ...................... 105 ns
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Context switch on Intel 5150 ............. 4,300 ns  =   4 µs

Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs

nelsnelson

# Did Mozilla F1 and Firefox Sync manage to duplicate your bookmarks 57814 times (like they did mine)?
# Did CheckPlaces and other misc addons completely fail at the task of removing duplicate bookmarks?
# Does the bookmarks manager grind to a halt even selecting an item?
# This is the fix for you..

# Backup the bookmarks in Firefox using the Backup function 
# (from the star icon in the bookmarks manager) to JSON.

# Invoke this script as following:
# ruby dupefixer.rb /Users/yourname/Desktop/bookmarks.json

nelsnelson

#! /usr/bin/env jruby

require 'rubygems'
require 'sequel'

gem 'jdbc-postgres'

DB = Sequel.connect('jdbc:postgresql://localhost:5432/test?user=test&password=test')

DB.create_table? :test do