Definition
Progress (Concurrency)
Progress is a liveness requirement for solutions to the critical section problem. it states that if no process is currently in its critical section and one or more processes wish to enter, the selection of the process that will enter next cannot be postponed indefinitely.
The “Progress” property ensures that the system as a whole continues to do work and does not get stuck in an infinite negotiation (e.g., a “you go first” situation where no one actually proceeds).
Analogy
The Polite Doorway: If two people reach a doorway at the same time and both endlessly insist that the other go first (“After you!”, “No, after you!”), they are failing the progress requirement. A valid solution must ensure that one of them eventually passes through.
Significance
The Progress property guarantees that the system is free from deadlocks regarding the entry into critical sections.