Ruby Threads and MySQL connection - mysql

Question

I'm trying the Ruby Threads, i have a simple script that need to iterate a json for getting certain data, all works fine but in one moment the shell shows:
`_query': This connection is in use by: #<Thread:0x00007f9c73973eb8#thread.rb:62 sleep> (Mysql2::Error)
How can i close that connection that i need for the data.
And the most important, the Threads are actually in the right way?
This is the script, it will run with a crontab:
require 'firebase'
require 'conekta'
require 'json'
require 'savon'
require "crack"
require 'active_support/core_ext/hash' #from_xml
require 'nokogiri'
require 'xmlsimple'
require 'mysql2'
class Cron
def generate_activation_code(size = 10)
charset = %w{ 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z}
(0...size).map{ charset.to_a[rand(charset.size)] }.join
end
def construct()
base_uri = 'FIREBASE_URL'
file = File.open("FIREBASE_CREDENTIALS", "rb")
firebase = Firebase::Client.new(base_uri, file.read)
Conekta.locale = :es
Conekta.api_key = 'MY_KEY'
#response = firebase.get('users', nil)
#client = Savon.client(wsdl: 'MY_URL', ntlm: ["user", "pass"] , :convert_request_keys_to => :camelcase )
#client_mysql = Mysql2::Client.new(:host => "localhost", :username => "root", :password => "", :database => "masaldo_api")
end
def get_comision()
last_validity = #client_mysql.query("SELECT comision * 100 as comision FROM configuration")
last_validity.each do |validityr|
#comision = validityr["comision"]
end
end
def create_transaction(sku, token, phone, userid, card)
validity = #client_mysql.query("SELECT precio * 100 as precio_total, vigencia, descripcion, precio as precio_base FROM bluesoft_services_validity WHERE sku='#{sku}'")
validity.each do |row|
#vigencia = row["vigencia"]
#descipcion = row["descripcion"]
#precio = row["precio_total"]
#precio_base = row["precio_base"].to_i
end
if #vigencia.to_i > 0
last_current = #client_mysql.query("SELECT * FROM transactions WHERE number='#{phone}' ORDER BY trandate DESC LIMIT 1")
last_current.each do |last|
#trandate = last["trandate"]
#trandate_result = #trandate.strftime("%Y%m%d %H:%M:%S")
end
end
#last_with_validty = (#trandate + (#vigencia).to_i.day).strftime("%Y-%m-%d")
#today = (Time.now).strftime("%Y-%m-%d")
if #last_with_validty == #today
conekta_charges = Conekta::Order.create({
:currency => "MXN",
:customer_info => {
:customer_id => user['customer_id']
},
:line_items => [{
:name => #descipcion,
:unit_price => #precio.to_i,
:quantity => 1
},
{
:name => 'Comision de Recarga',
:unit_price => #comision.to_i,
:quantity => 1
}],
:charges => [{
:payment_method => {
:type => "card",
:payment_source_id => user['fav_card']
}
}]
})
if conekta_charges['payment_status'] == 'paid'
begin
response = #client.call(:venta, message: { 'sku' => 'TELCPA100MXN', 'fechaLocal' => '20180117 14:55:00', 'referencia' => '818181818181', 'monto' => '100', 'id_cadena' => '30', 'id_tienda' => '30', 'id_terminal' => '1', 'folio' => 'LUCOPCIHOW' })
parameters = response.body
parameters.each do |response, data|
if data[:return][:respuesta][:codigo_respuesta] == 0
puts data[:return][:respuesta]
else
puts data[:return][:respuesta]
end
end
rescue Exception => e
puts e.message
puts e.backtrace.inspect
end
end
end
end
def init()
threads = []
hash = #response.body
hash.each do |token , user|
threads << Thread.new do
#Check if user is current for transaction if not need to check agenda
if user['is_current']
self.create_transaction(user['sku'], token, user['phoneNumber'], user['customer_id'], user['fav_card'])
user['addressBook'].each do |userid , user_address_book|
if user['is_current']
replacements = { '+521' => '' }
phone_number = user_address_book['phoneNumber'].gsub(Regexp.union(replacements.keys), replacements)
self.create_transaction(user_address_book['sku'], token, phone_number, user['customer_id'], user_address_book['fav_card'])
end
end
end
end
end
threads.each { |t| t.join }
end
end
classCron = Cron.new()
classCron.construct()
classCron.get_comision()
classCron.init()
Regards

Answer 1

When doing multi-threaded code in Ruby you'll need to be careful about not sharing resources like database connections between threads unless the driver makes it abundantly clear that kind of operation is supported. The ones I'm familiar with don't, and Mysql2 is not thread safe that way.
You can use Thread[:db] to store a local database connection per-thread, like:
def db
Thread.current[:db] ||= Mysql2::Client.new(...)
end
Where then you can refer to it like this:
db.query(...)
That will automatically instantiate the connection as required.
It's worth noting that mysql2 is a low-level driver and isn't very pleasant to use. A higher level abstraction like Sequel provides a number of significant benefits: Migrations, (optional) model layer, and a very robust query builder with support for placeholder values and easy escaping.