A mechanism is provided for handling interrupt actions for inter-thread communication. In association with a first processor thread, a thread action data structure is provided that comprises a non-blocking synchronization data structure and an internal list data structure of pending interrupts having no form of synchronization. A post of an interrupt action is received from a second processor thread to the thread action data structure associated with the first processor thread, where the interrupt action is added to the non-blocking synchronization data structure of the thread action data structure. The interrupt action is moved from the non-blocking synchronization data structure to the internal list data structure of pending interrupts for handling by the first processor thread. The internal list data structure of pending interrupts is processed to thereby handle interrupt actions moved to the internal list data structure.