In a first thread of a process a determination is made that a current value at a target address is not a desired value. In response to this determination, a first application programming interface (API) is invoked to indicate that the first thread is to sleep and be woken up when a second thread modifies the value at the target address. When a second thread modifies the value at the target address, the second thread invokes a second API to indicate that the value at the target address has been modified. In response to the second API being invoked, the first thread is woken up.