Parallelizing methods in Rails

You can take a look at a new option in town: The futoroscope gem. As you can see by the announcing blog post it tries to solve the same problem you are facing, making simultaneous API query's. It seems to have pretty good support and good test coverage.

Ruby has the excellent promise gem. Your example would look like:

require 'future'

def method_one
...
def method_nth

def summary
  result1 = future { method_one }
  ......
  resultn = future { method_nth }
  collect_results result1, ..., resultn
end

Simple, isn't it? But let's get to more details. This is a future object:

result1 = future { method_one }

It means, the result1 is getting evaluated in the background. You can pass it around to other methods. But result1 doesn't have any result yet, it is still processing in the background. Think of passing around a Thread. But the major difference is - the moment you try to read it, instead of passing it around, it blocks and waits for the result at that point. So in the above example, all the result1 .. resultn variables will keep getting evaluated in the background, but when the time comes to collect the results, and when you try to actually read these values, the reads will wait for the queries to finish at that point.

Install the promise gem and try the below in Ruby console:

require 'future'
x = future { sleep 20; puts 'x calculated'; 10 }; nil
# adding a nil to the end so that x is not immediately tried to print in the console
y = future { sleep 25; puts 'y calculated'; 20 }; nil

# At this point, you'll still be using the console!
# The sleeps are happening in the background

# Now do:
x + y
# At this point, the program actually waits for the x & y future blocks to complete

Edit: Typo in result, should have been result1, change echo to puts