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Processing CSV files more fast with Fibers + EM.defer
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require 'bundler/setup' | |
require 'fiber' | |
require 'csv' | |
require 'pp' | |
require 'eventmachine' | |
def a_slow_api_call(row) | |
sleep 0.3 | |
row.collect(&:to_i).inject(&:+) | |
end | |
def another_api_call(row) | |
sleep 0.1 | |
row.collect(&:to_i).inject(&:+) * 2 | |
end | |
def consume(row) | |
return if row.nil? | |
long_process = Proc.new do | |
# call an API... | |
result_1 = a_slow_api_call(row) | |
# call other API... | |
result_2 = another_api_call(row) | |
data = [ row[0], row[1], result_1, result_2 ] | |
data | |
end | |
process_result = Proc.new do |data| | |
# do some stuff with data | |
puts "#{row[0].rjust(7, ' ')} - #{data[1]} - #{data[2]} - #{data[3]}" | |
end | |
EM.defer(long_process, process_result) | |
end | |
`rm -f xalala.csv ; touch xalala.csv` | |
`for i in $(seq 1 10000) ; do echo "$i;$(date +"%s")" >> xalala.csv ; done` | |
processor = Fiber.new do | |
csv = CSV.open('xalala.csv', col_sep: ';') | |
csv.each { |row| Fiber.yield row } | |
csv.close | |
end | |
EM.run do | |
while processor.alive? | |
consume(processor.resume) | |
end | |
EventMachine.add_periodic_timer(1) do | |
if EventMachine.defers_finished? | |
EventMachine.stop | |
true | |
else | |
false | |
end | |
end | |
end |
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