litch

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

litch

require 'rubygems'
require 'ffi-rzmq'
require 'benchmark'
require 'json'

TESTS = 100_000

def error_check(rc)
  if ZMQ::Util.resultcode_ok?(rc)
    false

litch

Keybase proof

I hereby claim:

• I am litch on github.
• I am litch (https://keybase.io/litch) on keybase.
• I have a public key whose fingerprint is 2274 BE70 B287 7742 C4B4 1112 D88C E0B2 D7D4 D12A

To claim this, I am signing this object:

litch

I've added some functionality recently to be able to search a business by old UUID's, and am going to check the performance of it. So this little snippet will create a million rows in each of two tables and I'll post the results here as I get them (currently it's creating the rows, very slowly, probably because of the 4x uuid generation then indexing on the uuid column and the merged_uuids columns (and the indexes).

CREATE EXTENSION IF NOT EXISTS "uuid-ossp" WITH SCHEMA public;
COMMENT ON EXTENSION "uuid-ossp" IS 'generate universally unique identifiers (UUIDs)';


CREATE TABLE test_record_uuid (
    id uuid DEFAULT uuid_generate_v4() NOT NULL,
    name character varying(255),

litch

=render @memory_page.approved_comments
= simple_form_for [@memory_page, Comment.new], html: {class: 'form-inline'} do |f|
  .form-inputs
    .row
      .col-md-12
        = f.input :comment, label: "Add Your Comment", input_html: {class: 'editable'}
    .row#hidden_form_elements.hide //I have some JS callback that will display these fields once the parent input has been edited
      .col-md-6
        = f.input :name
      .col-md-6

litch

☺ ~% irb
>> Time.now.to_s
=> "2013-11-26 09:33:52 -0600"
>> "2013-11-26 09:33:52 -0600".to_datetime
NoMethodError: undefined method `to_datetime' for "2013-11-26 09:33:52 -0600":String
	from (irb):2
	from /Users/litch/.rvm/rubies/ruby-2.0.0-p247/bin/irb:13:in `<main>'
>> "2013-11-26 09:33:52 -0600".to_time
NoMethodError: undefined method `to_time' for "2013-11-26 09:33:52 -0600":String
	from (irb):3

litch

require 'redis'
require 'benchmark'

module ModuleMethods

  def self.record_metric(name)
    $REDIS.lpush(translate_name(name), Time.now.to_f)
  end

  def self.translate_name(queue)

litch

?> def get_memory_usage
>>   `ps -o rss= -p #{Process.pid}`.to_i
>> end
=> nil
>> 
?> before = get_memory_usage
=> 20296
>> 
?> n.times {MethodRegexObject.new}

litch

class PercentileFinder
  attr_accessor :action, :controller, :limit, :calls, :dataset

  def initialize(action, controller, limit = 1000)
    self.action = action
    self.controller = controller
    self.limit = limit
  end

  def find(percentile_looking_for = 0.95)

litch

require 'rspec/autorun'
require 'benchmark'

describe "polish notation" do
  it "do a trivial case" do
    polish_parser(:+, 1, 1).first.should == 2
    reverse_stack_polish_parser(:+, 1, 1).first.should == 2
    pm_polish_parser(:+, 1, 1).first.should == 2
  end