Question

In MRI Ruby I can do this:

def transfer
  internal_server = self.init_server
  pid = fork do
    internal_server.run
  end

  # Make the server process run independently.
  Process.detach(pid)

  internal_client = self.init_client
  # Do other stuff with connecting to internal_server...
  internal_client.post('some data')    
ensure
  # Kill server
  Process.kill('KILL', pid) if pid
end

However the above code will not run in jRuby, because it does not support ‘fork’ method:

NotImplementedError: fork is not available on this platform

Is there any alternative solution for this in jRuby?

Thanks.

Answer 1

I found out the solution for this. We can use the built-in library FFI in JRuby to ‘simulate’ the Process.fork in MRI.

# To mimic the Process.fork in MRI Ruby
module JRubyProcess
  require 'ffi'
  extend FFI::Library
  ffi_lib FFI::Library::LIBC
  attach_function :fork, [], :int
end

pid = JRubyProcess.fork do
  #internal_server.run
end

More details:

https://github.com/ffi/ffi

http://blog.headius.com/2008/10/ffi-for-ruby-now-available.html