Thread Lifecycle

A thread can exist in multiple states: NEW, RUNNABLE, WAIT, TIMED_WAITING, BLOCKED, or TERMINATED. A thread doesn’t begin its execution with its instantiation. Figure below shows the various phases of a thread, including the methods that can be called on a thread object in each state, which makes it transition from one state to another.

Note:

Thread scheduling is specific to the underlying OS on every system. As a programmer, you can’t control or determine when a particular thread transitions from the READY state to the RUNNING state, and when it actually gets to execute. A thread scheduler fol- lows various scheduling mechanisms to utilize a processor efficiently, and also to give a fair share of processor time to each thread. It might suspend a running thread to give way to other READY threads and it might execute it later. The READY and the RUNNING states are together referred to as the RUNNABLE state.