4 ms·

The disk did not fail. An I/O operation failed. The first is a permanent condition, the second can be permanent or transient. Big difference. In Linux a sig

by Avernar 10y ago

The disk did not fail. An I/O operation failed. The first is a permanent condition, the second can be permanent or transient. Big difference. In Linux a signal can cause an I/O to fail. In Windows it's antivirus and other background tasks can cause I/O to fail. What can it do to recover? Retry the I/O operation! It should keep trying until the operator tells it to stop.

sillysaurus3 10y ago
In that scenario, your surgeon would see the program suddenly freeze. The program likely looks like this: data acquisition -> transformation -> display transformation on monitor. If the transformation step fails, the monitor will end up displaying (a) nothing, (b) random data, or (c) the most recent image. None of these help the surgeon continue surgery. It's the same as a crash. If your environment fails, there's nothing you can do to recover. Planes aren't designed to survive the loss of a wing. Why is this case any different?
- Avernar 10y ago
  > In that scenario, your surgeon would see the program suddenly freeze. Only if the programmer or his management were incompetent. The display routine should be running on a separate thread than the processing code. No whole program freeze should occur. As for displaying random data, why would the programmer want to do this? Either display nothing or the last readings WITH a message that it's not real time. It's not the same as a crash! A crash requires 5 minutes minimum guaranteed. Restarting instantly after telemetry returns can happen under a second in the best case which can be the difference between a live and dead patient. > If your environment fails, there's nothing you can do to recover. Planes aren't designed to survive the loss of a wing. Why is this case any different? There are different kinds of failure. Permanent and transient. Following the permanent procedure for a transient case can be fatal. Take your airplane example. Loss of a wing is permanent. That would be like the CPU failing or an external cable being cut. But your engines shutting down can be permanent or transient. Just like disk I/O failing. You'd use the transient procedure in this case. Keep trying to restart the engines. If they restart, great! You've just saved the plane. Same with the disk I/O. The programmer should keep trying to restart the I/O. If it comes back, great! You've just saved the patient.
  - wpietri 10y ago
    Definitely. Each component should do its best to keep on keeping on. The display program should keep displaying something, even it's just the most recent data with a big "connection lost" warning. The device should ring-buffer the data and upon reconnection the screen should show as much as possible. The OS should have a strong opinion that the surgery app is very important, and that should the app fail, it should be restarted instantly. Moreover, this is the kind of thing that should come up in robustness testing. Things should get bumped and wiggled. They should get unplugged and turned off. If the software is really going to run on random Windows boxes, then it should be tested on random Windows boxes. (At which point somebody will hopefully say, "Wow, this sucks, let's make it an appliance.") No matter what happens, it shouldn't result in a "mysterious crash right in the middle of a heart procedure when the screen went black and doctors had to reboot their computer".
  - sillysaurus3 10y ago
    I had to step away from this conversation because of how aggressive you were being. Now that no one is watching, we might try to have a productive conversation. Please consider dropping the adversarial attitude. This place isn't like other sites. The way people converse is equally important to what they say. It's better to transcend than to dominate. For example, we do not slip in underhanded comments like this: > In that scenario, your surgeon would see the program suddenly freeze. Only if the programmer or his management were incompetent This is just short of a personal attack, which is against the rules. I know you probably didn't mean it that way, but look at how you're framing the debate. I felt as if I'd been teleported onto Fox News and forced to defend myself from an aggressive interviewer's mischaracterizations. Now, you can take the stance that "It's not against the rules, so I can say whatever I want." That's true, you can. But we're worse off for it. We optimize for good conversation here. The point I'm trying to get across is that if you really throw yourself into this community, wholeheartedly and without a feeling of having to prove something wherever you go, then this place has a lot to offer. You'll meet a lot of interesting people, you'll hear a lot of interesting stories, and perhaps you'll have an opportunity to contribute to something quite unexpected. But none of that will happen if you try to skewer your opponents wherever you go -- or if you see people here as opponents. We're people. It doesn't matter what the conversation is. It doesn't matter whether it's about life-or-death, or that this one happened to be about a surgery. The goal is to put yourself in the other person's shoes and to ask yourself, "If I were them, why would I say that?" Regarding our conversation, if you want to continue it, I'd be happy to. But unless you're trying to learn as much from me as I'm trying to learn from you, it's not going to go anywhere productive. And what would be the point? No one's looking anymore -- it's fallen off the front page, so it's just you and me here. But why should our conversation be so different just because nobody is watching? There are things to be said, but I have no time to defend myself. You can characterize what I was saying however you want. Or, alternatively, you could ask me what I meant. I won't pull one of those "I've been in the field for a pretty long time, so I bet you'll learn something..." routines. Those are tired refrains, usually coming from people who have long forgotten what it's like to be young and hungry. But I'm still pretty young, and money's low enough that I'm pretty hungry. Being unable to afford meat is unfortunate, but it's worth not having a job for a little while to throw myself into my research. See why there's no time to defend against aggression? I think I wrote this because in many ways, you remind me of how I used to be. And if I could go back in time, I'd ask myself what I was doing and why. This type of discourse is an intellectual dead-end. No one is going to learn a thing from watching people try to tear each other apart. Maybe you didn't realize that's what you were doing. It's very easy to slip into that mindset without realizing it. As for displaying random data, why would the programmer want to do this? GPUs are bastards. They ignore what programmers want, almost by definition. And as someone who has spent way-too-many years wringing as much performance as possible from them, I assure you that this is a realistic characterization of a possible outcome. Perhaps that piques your curiosity. If so, then that sounds like the start of a good conversation, no?
- Retric 10y ago
  Some aircraft have landed without all their wings. Fail fast is fine for a dating app, it's not acceptable for a antilock breaking system. As to disk IO they should have kept a redundant disk for backup just in case. Remember a program can generally spend 0.05 seconds waiting and no big deal. A program that takes 300 seconds to reboot is far worse.

by Avernar 10y ago

sillysaurus3 10y ago

In that scenario, your surgeon would see the program suddenly freeze. The program likely looks like this: data acquisition -> transformation -> display transformation on monitor. If the transformation step fails, the monitor will end up displaying (a) nothing, (b) random data, or (c) the most recent image. None of these help the surgeon continue surgery. It's the same as a crash. If your environment fails, there's nothing you can do to recover. Planes aren't designed to survive the loss of a wing. Why is this case any different?

Avernar 10y ago
> In that scenario, your surgeon would see the program suddenly freeze. Only if the programmer or his management were incompetent. The display routine should be running on a separate thread than the processing code. No whole program freeze should occur. As for displaying random data, why would the programmer want to do this? Either display nothing or the last readings WITH a message that it's not real time. It's not the same as a crash! A crash requires 5 minutes minimum guaranteed. Restarting instantly after telemetry returns can happen under a second in the best case which can be the difference between a live and dead patient. > If your environment fails, there's nothing you can do to recover. Planes aren't designed to survive the loss of a wing. Why is this case any different? There are different kinds of failure. Permanent and transient. Following the permanent procedure for a transient case can be fatal. Take your airplane example. Loss of a wing is permanent. That would be like the CPU failing or an external cable being cut. But your engines shutting down can be permanent or transient. Just like disk I/O failing. You'd use the transient procedure in this case. Keep trying to restart the engines. If they restart, great! You've just saved the plane. Same with the disk I/O. The programmer should keep trying to restart the I/O. If it comes back, great! You've just saved the patient.
- wpietri 10y ago
  Definitely. Each component should do its best to keep on keeping on. The display program should keep displaying something, even it's just the most recent data with a big "connection lost" warning. The device should ring-buffer the data and upon reconnection the screen should show as much as possible. The OS should have a strong opinion that the surgery app is very important, and that should the app fail, it should be restarted instantly. Moreover, this is the kind of thing that should come up in robustness testing. Things should get bumped and wiggled. They should get unplugged and turned off. If the software is really going to run on random Windows boxes, then it should be tested on random Windows boxes. (At which point somebody will hopefully say, "Wow, this sucks, let's make it an appliance.") No matter what happens, it shouldn't result in a "mysterious crash right in the middle of a heart procedure when the screen went black and doctors had to reboot their computer".
- sillysaurus3 10y ago
  I had to step away from this conversation because of how aggressive you were being. Now that no one is watching, we might try to have a productive conversation. Please consider dropping the adversarial attitude. This place isn't like other sites. The way people converse is equally important to what they say. It's better to transcend than to dominate. For example, we do not slip in underhanded comments like this: > In that scenario, your surgeon would see the program suddenly freeze. Only if the programmer or his management were incompetent This is just short of a personal attack, which is against the rules. I know you probably didn't mean it that way, but look at how you're framing the debate. I felt as if I'd been teleported onto Fox News and forced to defend myself from an aggressive interviewer's mischaracterizations. Now, you can take the stance that "It's not against the rules, so I can say whatever I want." That's true, you can. But we're worse off for it. We optimize for good conversation here. The point I'm trying to get across is that if you really throw yourself into this community, wholeheartedly and without a feeling of having to prove something wherever you go, then this place has a lot to offer. You'll meet a lot of interesting people, you'll hear a lot of interesting stories, and perhaps you'll have an opportunity to contribute to something quite unexpected. But none of that will happen if you try to skewer your opponents wherever you go -- or if you see people here as opponents. We're people. It doesn't matter what the conversation is. It doesn't matter whether it's about life-or-death, or that this one happened to be about a surgery. The goal is to put yourself in the other person's shoes and to ask yourself, "If I were them, why would I say that?" Regarding our conversation, if you want to continue it, I'd be happy to. But unless you're trying to learn as much from me as I'm trying to learn from you, it's not going to go anywhere productive. And what would be the point? No one's looking anymore -- it's fallen off the front page, so it's just you and me here. But why should our conversation be so different just because nobody is watching? There are things to be said, but I have no time to defend myself. You can characterize what I was saying however you want. Or, alternatively, you could ask me what I meant. I won't pull one of those "I've been in the field for a pretty long time, so I bet you'll learn something..." routines. Those are tired refrains, usually coming from people who have long forgotten what it's like to be young and hungry. But I'm still pretty young, and money's low enough that I'm pretty hungry. Being unable to afford meat is unfortunate, but it's worth not having a job for a little while to throw myself into my research. See why there's no time to defend against aggression? I think I wrote this because in many ways, you remind me of how I used to be. And if I could go back in time, I'd ask myself what I was doing and why. This type of discourse is an intellectual dead-end. No one is going to learn a thing from watching people try to tear each other apart. Maybe you didn't realize that's what you were doing. It's very easy to slip into that mindset without realizing it. As for displaying random data, why would the programmer want to do this? GPUs are bastards. They ignore what programmers want, almost by definition. And as someone who has spent way-too-many years wringing as much performance as possible from them, I assure you that this is a realistic characterization of a possible outcome. Perhaps that piques your curiosity. If so, then that sounds like the start of a good conversation, no?
Retric 10y ago
Some aircraft have landed without all their wings. Fail fast is fine for a dating app, it's not acceptable for a antilock breaking system. As to disk IO they should have kept a redundant disk for backup just in case. Remember a program can generally spend 0.05 seconds waiting and no big deal. A program that takes 300 seconds to reboot is far worse.