benolee

# frozen_string_literal: true

class SafeHash < Hash
  def initialize(namespace)
    @namespace = namespace
    @lock = Concurrent::ReadWriteLock.new
    super
    merge!({ @namespace => Concurrent::Map.new })
  end

benolee

class TBQueue
  def initialize size
    tvar = Concurrent::TVar

    @read = tvar.new []
    @write = tvar.new []
    @rsize = tvar.new 0
    @wsize = tvar.new size
  end

benolee

Scaling your API with rate limiters

The following are examples of the four types rate limiters discussed in the accompanying blog post. In the examples below I've used pseudocode-like Ruby, so if you're unfamiliar with Ruby you should be able to easily translate this approach to other languages. Complete examples in Ruby are also provided later in this gist.

In most cases you'll want all these examples to be classes, but I've used simple functions here to keep the code samples brief.

Request rate limiter

This uses a basic token bucket algorithm and relies on the fact that Redis scripts execute atomically. No other operations can run between fetching the count and writing the new count.

benolee

require 'fiber'
require 'concurrent' # gem install concurrent-ruby
Thread.abort_on_exception = true

class Async
  def self.perform(&block)
    instance = new
    instance.instance_eval(&block)
    until instance.dispatched.value.zero? do
      unless instance.yields.empty?

benolee

This is Japanese-English translation of my diary articles

• http://www.atdot.net/~ko1/diary/201502.html#d16
• http://www.atdot.net/~ko1/diary/201502.html#d17

These articles demonstration how to find out memory issues and tuning.

• How to estimate memory consumption
• How to use allocation_tracer gem to know object creation details
• How to optimize this typical issue in VM optimization

benolee

---

break /home/shim/Documents/foreman/dynflow/lib/dynflow/utils.rb:60

Why do we need indifferent_hash while saving?

 "/home/shim/Documents/foreman/dynflow/lib/dynflow/utils.rb:60:in `indifferent_hash'",
 "/home/shim/Documents/foreman/dynflow/lib/dynflow/persistence_adapters/sequel.rb:268:in `extract_metadata'",
 "/home/shim/Documents/foreman/dynflow/lib/dynflow/persistence_adapters/sequel.rb:226:in `prepare_record'",
 "/home/shim/Documents/foreman/dynflow/lib/dynflow/persistence_adapters/sequel.rb:236:in `save'",
 "/home/shim/Documents/foreman/dynflow/lib/dynflow/persistence_adapters/sequel.rb:125:in `save_action'",

benolee

From https://github.com/GhostGroup/infrastructure/pull/180

Header verification

Use socat to eavesdrop on the Nginx -> Unicorn socket-based comms.

ubuntu@ip-10-0-191-247:/etc/nginx/sites-enabled$ SOCK=/var/www/shared/.unicorn.sock [49/144]

benolee

#!/bin/bash
source mysql_access
TODAY=$(date +"%Y-%m-%d_%H%M%S")

CHECK_RETAINER=$(
                 mysql api_test \
                   -u$MYSQL_USER \
                   -p$MYSQL_PASS \
                   -h$SOURCE_HOST \
                   --socket=$MYSQL_SOCK \

benolee

Debugging ruby performance - Aman Gupta

C, Linux, networks, cpu, and memory usage

• lsof -nPp <pid>
• tcpdump
• write the data to a file, load it up in wireshark
• strace, trace systems calls and signals (jump into kernelspace)
• SIGVTALRM, ruby 1.8 every 10msec to switch threads (green threads)
• posix-spawn instead of fork-exec, check out posix-spawn gem
• ltrace

– ltrace -c ruby foo.rb # summary mode

benolee

Introduction

An introduction to curl using GitHub's API

The Basics

Makes a basic GET request to the specifed URI

curl https://api.github.com/users/caspyin