marcosgz

MAX_DISTANCE_AWAY_IN_KM = 100.0
RAD_PER_DEG             = 0.017453293

Rmiles  = 3956           # radius of the great circle in miles
Rkm     = 6371           # radius in kilometers, some algorithms use 6367
Rfeet   = Rmiles * 5282  # radius in feet
Rmeters = Rkm * 1000     # radius in meters

def haversine_distance( lat1, lon1, lat2, lon2 )
  dlon = lon2 - lon1

marcosgz

My largest Sidekiq application had a memory leak and I was able to find and fix it in just few hours spent on analyzing Ruby's heap. In this post I'll show my profiling setup.

As you might know Ruby 2.1 introduced a few great changes to ObjectSpace, so now it's much easier to find a line of code that is allocating too many objects. Here is great post explaining how it's working.

I was too lazy to set up some seeding and run it locally, so I checked that test suite passes when profiling is enabled and pushed debugging to production. Production environment also suited me better since my jobs data can't be fully random generated.

So, in order to profile your worker, add this to your Sidekiq configuration:

if ENV["PROFILE"]

marcosgz

Instrument Fog Requests in Rails

This code adds debug statements to the rails log for each fog reqests (similar to how active record shows SQL queries):

Fog AWS Compute Request (803.0ms)  [ {"Action"=>"DescribeInstances", ...} ]

The end of the request includes cumulative Fog info:

Completed 200 OK in 6043ms (Views: 2955.0ms | ActiveRecord: 319.9ms | Fog: 1642.6ms, 4 reqs)

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#!/usr/bin/env ruby
require 'net/telnet'

key_prefix = 'www.your:prefix'
cache_dump_limit = 1000

localhost = Net::Telnet::new("Host" => "localhost", "Port" => 11211, "Timeout" => 3)
slab_ids = []
localhost.cmd("String" => "stats items", "Match" => /^END/) do |c|
  matches = c.scan(/STAT items:(\d+):/)

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# this monit config goes in /etc/monit/conf.d

check process puma_master
  with pidfile  /data/myapp/current/tmp/puma.pid
  start program = "/etc/monit/scripts/puma start"
  stop program = "/etc/monit/scripts/puma stop" 
  group myapp

check process puma_worker_0
  with pidfile /data/myapp/current/tmp/puma_worker_0.pid

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class BooleanValue
  # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/column.rb#L8
  FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'off', 'OFF']

  def self.from_string(value)
    Rails.present? ? with_rails(value) : without_rails(value)
  end

  private

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-- 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%' 

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require 'openssl'

key = OpenSSL::PKey::RSA.new(2048)
p encrypted_string = key.public_encrypt('my plaintext string', OpenSSL::PKey::RSA::PKCS1_OAEP_PADDING)
p decrypted_string = key.private_decrypt(encrypted_string, OpenSSL::PKey::RSA::PKCS1_OAEP_PADDING)

marcosgz

# ~ Dispatch jQuery events as regular DOM events ~
#
# Delegated events are given a new name in the format `jquery:<original event name>`.
# If you delegate `ajax:send` you will be able to listen for `jquery:ajax:send`
# on native event listeners such as Stimulus actions and `EventTarget.addEventListener`.
#
# Notes:
#   * The first parameter must be called "event".
#   * The parameters can be accessed as members on the `event.detail` object.
#