mysql2_prepare.rb

require 'mysql2'

client = Mysql2::Client.new(
  host: 'localhost',
  username: 'root',
  database: 'mysql',
)

begin
  num = 0
  2000.times do |n|
    num = n
    stmt = client.prepare('SELECT * FROM user LIMIT 1')
    stmt.execute
    #stmt.close
    #GC.start
  end
rescue
  p num
  p $!
end