when does a process enters a blocked state
Process state A process transitions to a blocked state when it cannot carry on without an external change in state or event occurring. For example, a process may block on a call to an I/O device such as a printer, if the printer is not available. Processes also commonly block when they require user input, or require access to a critical section which must be executed atomically. Such critical sections are protected using a synchronization object such as a semaphore or mutex.
Clock management Upon kickoff, the clock is started when a member of the receiving team touches the ball, or, if the member of the receiving team touches the ball in their end zone, carries the ball out of the end zone. The clock is stopped when that player is tackled or goes out of bounds. (The clock never starts if the receiving team downs the ball in their own end zone for a touchback.) The clock is then restarted when the offense snaps the ball for their first play and continues to run unless one of the following occurs, in which case the clock is stopped at the end of the play and restarts at the next snap unless otherwise provided:[1]