4 ms·

> The language I'm speaking of is designed for real-time high-reliability scenarios where ease of programming takes the back seat to correctness and determinism

by ramchip 11y ago

> The language I'm speaking of is designed for real-time high-reliability scenarios where ease of programming takes the back seat to correctness and determinism. It sounds like the opposite - the setup allows for a low priority task to block every other task, which is normally the last thing you'd want in such a system.

tormeh 11y ago
Yes, this is a weakness of the model, but the key strength is that it will do so every time, which makes it way easier to test than the alternatives. Real-time doesn't mean that performance is as high as possible, it means that you can guarantee a certain level of responsiveness. A language can't do that for you, but it can help, which is why people use Esterel.
- lkrubner 11y ago
  "Real-time doesn't mean that performance is as high as possible" At one time "real-time" actually meant "real-time" as in "the sensor that determines whether to deploy the air bag in your car makes its decision in less than a ten thousandth of a second." Nowadays, people are using "real-time" to refer to things that don't come close to being real time. If you allow a single thread to block all other threads than a thread engaging in a slow I/O operation could potentially block your whole app for several seconds. If that is the new definition of "real-time" than the phrase has become meaningless.
  - chrisseaton 11y ago
    It sounds like you think real-time just means 'fast'. I don't think it ever meant that. In my mind it's about guarantees. 0.1ms to decide to deploy an airbag is a real-time guarantee, but so is 3s to decide to do something on a whole different scale like close a fire door. So if the slowest thread blocks you, but you know it can't block you for longer than you care about, then that's still real-time.
  - maattdd 11y ago
    Real-time is about guarantee, not speed. I suggest you to read the Wikipedia article which is pretty clear https://en.wikipedia.org/wiki/Real-time_computing https://en.wikipedia.org/wiki/Real-time_computing

by ramchip 11y ago

tormeh 11y ago

Yes, this is a weakness of the model, but the key strength is that it will do so every time, which makes it way easier to test than the alternatives. Real-time doesn't mean that performance is as high as possible, it means that you can guarantee a certain level of responsiveness. A language can't do that for you, but it can help, which is why people use Esterel.

lkrubner 11y ago
"Real-time doesn't mean that performance is as high as possible" At one time "real-time" actually meant "real-time" as in "the sensor that determines whether to deploy the air bag in your car makes its decision in less than a ten thousandth of a second." Nowadays, people are using "real-time" to refer to things that don't come close to being real time. If you allow a single thread to block all other threads than a thread engaging in a slow I/O operation could potentially block your whole app for several seconds. If that is the new definition of "real-time" than the phrase has become meaningless.
- chrisseaton 11y ago
  It sounds like you think real-time just means 'fast'. I don't think it ever meant that. In my mind it's about guarantees. 0.1ms to decide to deploy an airbag is a real-time guarantee, but so is 3s to decide to do something on a whole different scale like close a fire door. So if the slowest thread blocks you, but you know it can't block you for longer than you care about, then that's still real-time.
- maattdd 11y ago
  Real-time is about guarantee, not speed. I suggest you to read the Wikipedia article which is pretty clear https://en.wikipedia.org/wiki/Real-time_computing https://en.wikipedia.org/wiki/Real-time_computing