the first step should always be to check the help in the plugin's page in the plugin manager, or if that fails go to the website where you got the plugin from.
and if you still need help after that, you should at least link to where you got the plugin from so that we can check it.
When I learned about multithreading in C++, one of the first things was that while heap is shared, each thread has its own stack and it's impossible to access another thread's stack.
So I wrapped the variables into a static class and passed its address to another thread. And it worked.