Using JSON in a Ruboto project

Question

I've got two different projects written in Ruby, using Ruboto to pack the Ruby into an .apk so it can be pushed onto an Android device. Both projects will compile and run on my phone as well as a phone emulator, but adding the line 'require 'json'' in both projects, changing nothing else, cause them to fail on startup and kick me back to the phone homepage. So it's definitely something with that line. Any ideas on what could cause this?

Answer 1

I had the same problem; you can use

adb logcat

to get more information about the crash. If you look there, you will find an error message about a stack overflow . You can circumvent this stack overflow by requiring only json/pure:

require 'json/pure'

This still does not help with the general problem: most require calls lead to a stack overflow. Via Google, I found that Android is not able to have too many nested recursive calls, only about 22, until it crashes with a stack overflow. The solution I was pointed to was to use iteration, instead of recursion. :)

So right now, I know of no real solution. Most big or useful gems result in the same problem, e.g. yaml, httpi, or nokogiri.

Edit: There is a similar question in the Google mailing-list.

Answer 2

Ruboto offers a helper method to run code with increased stack size:

require 'ruboto/util/stack'

with_large_stack{require 'json'}

or

with_large_stack do
  require 'json'
end

This will run your code in a separate thread with larger stack allowing deep recursion. The default stack size for the with_large_stack method is 64KB. You can set this value using an optional integer argument or the option hash:

with_large_stack(128){require 'json'}

or

with_large_stack(:size => 128){require 'json'}

The stack size is given in kilobytes (KB).