You don't show how you "made that method threaded"?
I'd hazzard a guess that you are attempting to share one or more objects between threads via closures--and that doesn't work!
You'll need to show the full code if you want a resolution.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.