Accessing function in multithreading environment in c++

I am currently working on multi-threaded C++ application using c++11 standard thread application. I am using two third party libraries which are also multithreaded libraries. The development platform is linux. In my application I am using callbacks provided by these two third party multithreaded libraries. When I do load test in which I bombard the application by 200ms interval from packet sender application I found that my application runs for 2 hours but after some time it hangs in one of the api provided by third party library. This application runs well without any problem in single threaded application. Can you please suggest me how to handle third party callbacks in multithreaded application so that I can prevent such type of application hang issue? I have used condition variable to achieve synchronization but still I am getting this problem. Please tell me solution to this problem thanks in advance