Thread and Channel

Goby interpreter adopts Golang for language implementations, mainly for fully utilizing Golang's concurrency mechanisms. Thus Goby naturally equips thread and channel feature with the help of underlying Golang.

Topics Related to Concurrency Programming

To understand more on concurrency programming, there are some resources we recommended you to read through it:

• Concurrency is not Parallelism by Rob Pike
• Go's Concurrency Pattern by Rob Pike
• Introduction to Concurrency Models in Ruby Part (I) on Medium by exAspArk
• Introduction to Concurrency Models in Ruby Part (II) on Medium by exAspArk

Thread

Every Goby thread runs on a new goroutine. And unlike Ruby, there's no Thread class in Goby. To create a thread, just use thread method with a do - end block:

thread do
  # Write whatever you want to do
end

Goby's do - endblock is transparent for variables and it is possible to access variables across the thread block:

i = 0

thread do
  i += 1
  puts(i) #=> 1
end

This is convenient for manipulating data in many cases, but can cause some problems. You should avoid something like:

i = 0

1000.times do
  thread do    # avoid creating many threads repeatedly
    i += 1
  end
end

puts(i)

or

i = 0     
thread do
  i += 1        # avoid non-Channel variables for communicating outside
end

i += 1
i

Channel

To communicate between threads, we need to use Channel object to do that. Channel object has two methods: #deliver (passing object) and #receive (receiving object)

c = Channel.new

thread do
  c.deliver 10
end

puts(c.receive) #=> 10

And Goby's Channel inherits Go channel's blocking behavior, so you can use it to do flow control

c = Channel.new

i = 0
thread do
  i += 1
  c.deliver(i)
end

c.receive
i += 1 # This will not execute until the thread ends
i

But unlike Go's channel has type restriction, Goby's channel can pass everything. So it's possible to process one thing in other thread and send it back to main thread.

class Foo
  def bar
    100
  end
end

c = Channel.new

thread do
  f = Foo.new
  c.deliver(f)
end

puts(c.receive.bar) #=> 100