krakjoe/pthreads — pull request #269 by amezghal (2014-03-20 15:54:51+00:00)
Title: add second argument to the start() method, to allow exclude some global vars of being copyied 

this is very important, try to have a global variable which is an instance of PDO
it will not work if you want to keep global vars across scopes.

It will try to serialize the PDO instance (which is not possible)...