Under a lock free algorithm, we promise that across our entire system, eventually some progress is made. I can't necessarily point at any specific thread of exe

Under a lock free algorithm, we promise that across our entire system, eventually some progress is made. I can't necessarily point at any specific thread of execution and say "This thread makes progress" but I can say that forward progress is made for the system as a whole. Under a wait free algorithm, we promise that every individual thread eventually makes progress. Suppose I have one really dumb thread which just goes to sleep for 10 seconds in a loop, as well as other threads which do some actual work. If we're a lock free algorithm, it is OK if the 10-second-sleep thread is always chosen to make progress, its "progress" consists of sleeping for 10 seconds, too bad, try again next time. With a wait free algorithm, the threads which actually do useful work will also make at least some progress, eventually despite the 10 second sleeper. Generally we can't say for sure that we e.g. "reduce impact of contention" only that we definitely make some forward progress, on at least one thread eventually.