I have been playing with dmThread and I managed to get it working. See the attached project. I have tested on Windows only.
defold threads.zip (16.0 KB)
Threading example.zip (22.9 KB).
Added support for modules.
Threading example 2.zip (5.6 KB)
You can add the extension to your project through bitbucket.
Running modules is as simple as
local fname = "main/modulename.lua" thread.run2(fname, argument, "background_function", on_complete)