Detecting non-callable external component APIs is provided. It is determined whether a first function call stack of a worker thread in a multi-threaded application of the computer matches a second function call stack of the worker thread. In response to determining that the first function call stack matches the second function call stack of the worker thread, an external component application programming interface (API) corresponding to the worker thread is identified from a function call stack of the worker thread. The external component API corresponding to the worker thread is marked as non-callable in an API state map. The worker thread is marked as being in a hang state. The worker thread in the hang state is terminated as a remediation action step to maintain performance.