flush_backlog.rb

require 'pg'
require 'benchmark'

DATA = "a" * 100

rows = ARGV[0].to_i
rep_type = ARGV[1]

def time_bdr(target)
  local_conn = PGconn.connect(:dbname => 'vmdb_production')
  remote_conn = PGconn.connect(:host => target, :dbname => 'vmdb_production', :password => 'smartvm')
  remote_conn.exec("select bdr.bdr_apply_resume()")

  Benchmark.realtime do
    loop do
      res = local_conn.exec("select pg_xlog_location_diff(pg_current_xlog_location(), flush_location) as lag_bytes from pg_stat_replication").first
      break if res && res['lag_bytes'].to_i == 0
      sleep(0.2)
    end
  end
ensure
  local_conn.close
  remote_conn.close
end

def pause_bdr_remote(target)
  conn = PGconn.connect(:host => target, :dbname => 'vmdb_production', :password => 'smartvm')
  conn.exec("select bdr.bdr_apply_pause()")
  sleep(1) until conn.exec("select bdr.bdr_apply_is_paused() as paused").first['paused'] == 't'
ensure
  conn.close
end

def time_rubyrep
  conn = PGconn.connect(:dbname => 'vmdb_production')
  pid = Process.spawn("bin/rake evm:dbsync:replicate", :chdir => "/var/www/miq/vmdb")

  Benchmark.realtime do
    loop do
      backlog = conn.exec("select count(id) from rr1_pending_changes where change_table = 'test'").first['count'].to_i
      break if backlog == 0
      sleep(0.2)
    end
  end
ensure
  begin
    Process.kill("INT", pid)
  rescue Errno::ESRCH
  end
end

def insert_rows(rows)
  conn = PGconn.connect(:dbname => 'vmdb_production')
  Benchmark.realtime do
    rows.times do |i|
      conn.exec("insert into test (id, data) values (#{i}, '#{DATA}')")
    end
  end
ensure
  conn.close
end

rep_time = 0
insert_time = 0
case rep_type
when "rubyrep"
  insert_time = insert_rows(rows)
  rep_time = time_rubyrep
when "bdr"
  rep_target = ARGV[2]
  pause_bdr_remote(rep_target)
  insert_time = insert_rows(rows)
  rep_time = time_bdr(rep_target)
end

puts "#{rep_type}:\n  insert took: #{insert_time.round(2)}s\n  replicated #{rows} rows in #{rep_time.round(2)}s"

results

rubyrep:
  1,000 rows:
    insert: 0.2
    replicate: 7.42
  1,000 rows:
    insert: 0.2
    replicate: 7.22
  10,000 rows:
    insert: 1.87
    replicate: 15.94
  10,000 rows:
    insert: 1.77
    replicate: 15.18
  100,000 rows:
    insert: 19.77
    replicate: 100.97
  100,000 rows:
    insert: 20.07
    replicate: 104.28
  1,000,000 rows:
    insert: 197.47
    replicate: 952.35
  1,000,000 rows:
    insert: 191.25
    replicate: 1005.44
bdr:
  1,000 rows:
    insert: 0.17
    replicate: 2.01
  1,000 rows:
    insert: 0.17
    replicate: 2.01
  10,000 rows:
    insert: 1.71
    replicate: 1.61
  10,000 rows:
    insert: 1.73
    replicate: 1.61
  100,000 rows:
    insert: 16.58
    replicate: 3.61
  100,000 rows:
    insert: 18.37
    replicate: 3.81
  1,000,000 rows:
    insert: 162.86
    replicate: 26.11
  1,000,000 rows:
    insert: 167.84
    replicate: 26.08