The fault lies in the bad software. It could have been the indexing service, online defrag, automatic updates, or any of the other various background processes windows runs.
If it is critical software, it should be designed in a way to not fail when something non-critical malfunctions, and even the critical pieces should be built with redundancy.
I'm not trying to excuse the company in the article or the company that I work for. And I do not work for the company in the article. I just wanted to point out that I do see how this can happen very easily and repeatedly.
One such system is Disti (http://www.disti.com/)
In the automotive field, our software is MISRA compliant, static analysis is done (Klockworks - http://www.klocwork.com/) and we follow a very strict set of guidelines outlined in ISO25119 and ISO26262 for the construction and agricultural markets. Think self driving tractors and combines. For example: A tractor traveling down a field with a combine following it a few rows over separating and chopping things into a catcher all done with one person driving.
This shit can't happen where I work. Every component on our circuit boards has a MTTFd of 40 years. Hardware watchdogs can kill the system if software goes awry.
Software is written to readiness level called SRL-1, SRL-2, etc... Unit tests, peer reviews, etc... Functional safety in medical devices is covered under 510(K) (http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedur...)
I find it amazingly short sited that antivirus software is even allowed on a medical device to begin with. I can't even imagine how this system even passed the easiest audit for software readiness.
How is it you "go hoarse having the same conversations?" Do you not have to meet FDA compliance criteria? Are you in the US?
I didn't read the whole article so I'm assuming this happened in the US. For me, we sell autonomous vehicles in the European markets where functional safety seems to be a bit more aggressive there right now for vehicles. Not sure about medical devices.
Well... Then you should consider yourself blessed to have never had to deal with the bureaucracy of a hospital IT department and administrative staff.
Who owns the medical device? Who paid for it? If it's a glorified Windows machine and it's attaching itself to a hospitals WiFi network... Who has to use this machine? Physicians, surgeons, anesthesiologists, radiologists, other specialists, nurses, staff? All of them need to be trained on it's usage, no doubt. They don't get that training in schooling. Who provides it? This and a million other things stack up. So, well, I mean it can start to make sense how these things end up with random AV software installed on them, right?
> How is it you "go hoarse having the same conversations?" Do you not have to meet FDA compliance criteria? Are you in the US?
Yes, we are. Yes, we do "have to meet FDA compliance." I can't define "have to meet" and I work here. Of course, I'm just an engineer. We have legal, executive, and other staff for those matters. I'm sorry, I'm not trying to be an asshole... I'm just trying to be honest about where I find myself in this situation.
If you are only making these warnings verbally, you might want to consider emailing your immediate manager with a list of concerns. Make it as neutral as possible and ask for guidance on how they want to address the issues. But if it's on the mail server, it will be good for discovery if the worst happens, and frankly given lives are at stake you probably need to show, in writing, that you were attempting to have the issues addressed.
Who knows? That might actually get traction. Might even save someone's life!
You are not an engineer. This is a protected term in the US and other countries. If you were a professional engineer, you would be bound by a legal and moral framework preventing you from doing work on unsafe medical equipment.
There is a good argument that there should be a software equivalent of protected engineer status for this kind of work. This kind of story should be a wake up call. I personally had no idea that critical medical equipment would be running on MS windows...
As of 2012 you can take the PE Exam for Software Engineering [1].
[1]: http://ncees.org/about-ncees/news/ncees-introduces-pe-exam-f...
You have to deal with FDA pretty much regardless where you're based, if you want any kind of market for your medical device. A lot of countries define compliance as whatever is good enough for FDA.
FDA rules for software... what FDA wants is a paper trail.
Unfortunately the only thing that can solve the apathetic board and executive management problem(who only see dollar signs) is the actuality, or realistic possibility, of significant financial loss, or loss of their personal freedom(prison) due to the negligence of the system. And a $10 Mil fine for a fault in something that you make $100 Mil off of is not significant. That's $90 Mil profit in their eyes. And they probably get to write it off.
Even more unfortunate, is that, in the situation that this happens, the "engineers responsible" will be fired, and the executives will resign with a nice golden parachute, and go on to do the same thing somewhere else.
But then you have the company that does do it right, spend the time, and the money to make a truly redundant, fault-tolerant system. But, they come in at a price point 20% higher than their competitor, who doesn't. Which company survives and which doesn't?
Sad, but, unfortunately the way it is. I don't know a practical solution either.
We've been close to undergoing "major" scrutiny (as it was sold to me, it was A Big Deal) from the FDA before. I, personally, just a lowly and underpaid engineer, have saved executive staff from having to sign their names on that noose. I had a manager once who seemed to want to push it that far, to stand idle-by while the walls fell down around us. I, unknowingly at the time, prevented it from happening because I was trying to help our customers. I don't regret that decision, actual patients shouldn't have to suffer because of a management teams ineptitude. I do think about it often, though. I understand this is nebulous, and I'm sorry for that. This is a reality, though.
I guess that's the thing that really gets me, the FDA. We sell FDA approved devices. Where the fuck is the FDA? We send them paperwork and they are happy. I can only form the opinion that they, the FDA, are ill prepared to handle this situation; The actual situation, the "the medical devices industry is a fucking train wreck waiting to happen" situation, and especially so they are ill prepared to handle it at scale. Audits are cursory and almost as a rule non-technical. I suppose it'll take a Toyota-level incident to bring change about.
I have seen SSAE16 audited companies that haven't patched anything in years. FDIC examined institutions with ATM machines still running OS/2 Warp(actually probably more secure than the ones running XP, with no updates installed. Ever.)
I once found the management interface of a SAN with a public IP address directly on the device, no firewall rules of any sort, and the device still had the default username/password. It hadn't been patched or rebooted in over 2 years.
More shocking is that a review of the logs didn't show any successful unauthorized logins. Of course, they could have cleaned up after themselves, but further investigation was outside the scope of my engagement(They didn't want to know. They were happy to present that, despite the oversight, there was no indication that PHI had been accessed by unauthorized people. Their conclusion, not mine.)
But as I've said before - I really hope you have written down your concerns to someone in management. If it gets to the point where negligence takes out the company, there's going to be an attempt to make someone a scapegoat. Depending on your role in the company you don't want to be held personally liable for the incompetence and ruthlessness of management...
When regulation becomes more about permission than proficiency, you'll get corruption instead of competence.
Or developers refuse to build software without safety built in.
If they can't hire anyone to build their unsafe systems, they'll have to start building safe software.
Let the market work for you.
If every developer on the planet suddenly had a pang of consciousness, then something like this would work.
Fortunately I have never found myself in such a position, but I have seen it many many times.
I generally oppose certification for engineers, but solving collective action dilemmas like this and saving lives in the process is exactly where it would help.
I know examples of people in licensed fields who have sworn to uphold a code of ethics, but have been caught up in very similar situations.
I can't find it now but I just saw a video recently of a rail bridge with a crumbling foundation that had just been signed off on by a PE and declared safe by the railroad.
A fine being tax deductible does not mean zero cost to the company, it means the profit is reduced before taxes are computed, i.e. the actual cost is reduced by the marginal tax rate. A tax credit means zero cost.
Presumably developers are the one's estimating how long things take. (If they're not, you have even bigger problems and I'm sorry.) The time to make it safe should automatically be included in those estimates.
Moreover, making it safe shouldn't be a separate part of the process. It should just be part of how you write software. It's either safe or it doesn't exist at all. (Compare this to how organizations like Google deal with concurrency: it's built in from the start.)
A reputable engineer wouldn't design and build a bridge which might collapse. A developer shouldn't build software which puts lives at risk, regardless of management pressure.
If they refuse to relent, there are plenty of jobs where safety isn't critical.
This is not meant as a slight: I think you're grossly unfamiliar with software development outside of engineering-driven companies.
It's pretty much a guarantee that product managers are deciding these estimates. They might confirm with the developers, but the conversation probably went something like this:
"Does 3 weeks sound about right for this?"
"No, we'll need 6"
"Why?"
"Safety checks"
"Ok, we don't have 6 weeks. I can give you 4, but we're just gonna have to make do."
Is it scary that conversation happened about a piece of medical software? Absolutely. Would I bet $1k that it happens frequently? Absolutely.
> A reputable engineer wouldn't design and build a bridge which might collapse
Rarely does a single engineer design a bridge nowadays, so corporate liability and reputation (good luck landing more contracts if your bridge collapses) is a huge factor in much of that beyond simple ethics.
I would be shocked if anything happened to Merge as a result of this, whereas a company who designed a faulty bridge would be sued into oblivion.
Further, professional engineering in the US is a whole different game that involves licensing and regulations specifically to avoid that situation. Software "engineering" has no such equivalent currently.
Pinning the blame on the peons is a sure-fire way to make sure this situation never changes.
The difference is that they never should get the decision to cut safety checks. Cutting safety checks should be as ludicrous/impossible as writing half the code of each function to cut time.
The conversation should go like this:
PM: "Does 3 weeks sound about right for this?"
Dev: "No, we'll need 6"
PM: "Why?"
Dev: "That's how long it takes to build those 6 features."
PM: "Ok, we don't have 6 weeks. I can give you 4, but we're just gonna have to make do."
Dev: "Okay, which features would you like to cut?"
> Further, professional engineering in the US is a whole different game that involves licensing and regulations specifically to avoid that situation.
I'm aware. While I don't think the majority of software developers should be certified, we should require licensing for working on safety-critical applications.
I think you're missing the end to that conversation:
>PM: "Ok, we don't have 6 weeks. I can give you 4, but we're just gonna have to make do."
> Dev: "Okay, which features would you like to cut?"
PM: We can't cut any of them. We need features A,B,C in the product and we need it in 4 weeks.
Here we insert a rant from the PM about one of the following:
1) Leadership
2) Hard work
3) Threats about job security
4) Recalling that one time you delivered something ahead of schedule so why is this different
5) I see you getting up to get coffee at least twice a day so stop goofing off and get it done
I think you're vastly overestimating how much power/control said Dev has over the whole process at these sorts of companies.
Sure, they can quit, but if they felt empowered to quit they probably wouldn't be there in the first place: I don't think anyone's busting down the door to work at MedicalBusinessTM.
> we should require licensing for working on safety-critical applications.
Fully agreed, though with some misgivings.
Incorporating safety-critical software into the "professional engineering" spectrum would almost certainly require some things that are seen as near-heresy to the software community, like requiring a 4-year degree from an ABET-accredited program.
Still, I agree.
> Incorporating safety-critical software into the "professional engineering" spectrum would almost certainly require some things that are seen as near-heresy to the software community, like requiring a 4-year degree from an ABET-accredited program.
The vast majority of software isn't safety-critical, so there would still be plenty of opportunities for developers who don't fit into rigid modes.
I 100% oppose having accreditations for all developers.
As ever, a relevant xkcd: https://xkcd.com/463/
We use a National Instruments DAQ card, and need the PC to respond within 50 ms to issue new commands for hours or days. Remarkably, it usually (over hundreds of machines and decades of operation) does. When it doesn't, it's blamed on antivirus or firewall or technicians using the PC for other things while the software runs.
National Instruments provides real-time IO systems, but they cost a lot more than the basic systems. You can write driver-layer code that will run in real-time on Windows, but that takes longer.
Our customers and management, with varying levels of comprehension of the problem, elect to not spend that money. I hate to say it, but if we didn't make this compromise, there are competitors who would.
It works as long as full code path and data it requires is not paged out. Or some other thread doesn't consume I/O resources, etc.
In other words, it's not guaranteed at all.
Only way to get Windows to react reliably within 50 ms is in a kernel driver, as response to an IRQ. There's considerable jitter even in IRQ, but usually worst case service times are 200-500 microseconds. Depends a lot on other devices and on your IRQ priority. It's worse for passive level drivers (IRQL == 0).
50 ms guaranteed response time requires the code and data is in non-paged pool.
For example, if there is a massive amount of data, it has to be stored on disk. It's too large to keep in memory. And if the point of the program is to transform that data in real time, then it has to have access to the disk.
The antivirus basically unplugged the disk. What can it do to recover? There's nothing to be done.
It should be able to survive that situation, of course. When the disk is plugged back in, it should be able to restart without any problems. But I think that's a different kind of resiliency than what you're referring to.
In this case, the only way to recover would be to copy the frozen data to a new area of the hard drive, assuming it retained read access. But such complexities result in brittle implementations, prone to acquiring bugs. What if the disk space runs out? So you check beforehand whether there's enough space. But what if some other program starts consuming disk space in the middle of your copy operation? And so on. It's an endless spiral of design complexity.
The situation in the article seems closer to hardware failure than a design oversight.
Yes and no. I was referring to restarting internally when the error condition went away but restarting the app and waiting for telemetry to return can be a valid solution.
Think of your torrent software. If you crank your firewall to block it while it's running it will not crash. If your disk fills up it won't crash. When the network comes back or more drive space if freed it will restart it's internal mechanisms. You wouldn't want it to restart in these conditions. If it runs out of memory however choosing to exit might be the best recovery mechanism.
I think a life critical medical application can at least strive for internal restart and do an external restart if all else failed. The article stated they had to reboot the machine to get it back. Now that's way worse.
> The situation in the article seems closer to hardware failure than a design oversight.
Hardware failure is almost always a permanent condition. This was a "my I/O stopped briefly and would have came back if my code could handle it".
A spectacular crash immediately led to pinpointing the problem: The antivirus.
If the program's sole purpose is to transform a massive amount of data in real time, it must have disk access by definition. It can't not have disk access. What would you suggest it do?
Immediately? Took them 5 minutes to reboot the computer. The scan of the folder would take seconds let alone minutes. Pinpointing the problem is secondary. Not killing the patient is primary.
> If the program's sole purpose is to transform a massive amount of data in real time, it must have disk access by definition. It can't not have disk access.
And that is the mind set the programmers of the software had. You have to take care of error conditions. The processing can't have no disk access but no disk access can occur temporarily or permanently. What can you do? Pause the processing part of your program. Or make the processing part treat "no data" as valid input and display something else.
Imagine taking that viewpoint with an ECG machine: This machine displays a heart rate waveform. So it must have a heart rate input. If there is no heart rate we'll just crash requiring a 5 minute reboot.
Hell no! Draw a straight line and set off a buzzer!
Exactly. Which is why "Can't read file sensors.dat" is way better than just crashing. Crashing is one of the worst error messages you can get because you don't know what happened.
Yes it does! Showing "no telemetry available" is exactly what it should do. Crashing = unreliable. Reporting an error condition = reliable.
Immediately? Took them 5 minutes to reboot the computer. The scan of the folder would take seconds let alone minutes. Pinpointing the problem is secondary. Not killing the patient is primary."
Well-put. Far back as Burroughs B5000, the best way to handle erroneous software or I/O was to freeze it, notify the administrator/user of the problem, and give them sensible options for how to proceed. They might restart the I/O, restart the app, modify erroneous data to proceed (rare here), and so on. Crash and reboot is a Windows 95/NT strategy where incompetence dominated. Today's Windows OS and tooling can do much better with little effort by developers.
In a situation like this, confusion is all but inevitable. As a developer, the goal should be to minimize that confusion to the greatest extent possible. A blank screen and crash introduces another step to the process as people wonder "what's going on?" instead of "shit, it threw an error." It's probably not a big deal, but with medical devices during surgery, that extra step could be hugely problematic.
Sure, usually the most graceful thing to do is exit and hope a human fixes it. But that's usual because the usual condition is that sudden failure is NBD and a human is right there to screw with it.
That's becoming less common, though. When software was mostly something running on a PC doing some boring office task, reliability didn't matter. But as software is running our airplanes, our cars, our medical devices, and even, as with implanted pacemakers and insulin pumps, our bodies, then reliability gos from NBD to BFD.
We see the way forward with things Chaos Monkey [1] and crash-only software [2] and the sort of design for failure you see in things like Agent supervisor hierarchies [3], where the way to reliability is through designing for failure recovery from the beginning and testing thoroughly to make sure it really happens.
[1] https://github.com/Netflix/SimianArmy/wiki/Chaos-Monkey
[2] https://en.wikipedia.org/wiki/Crash-only_software
[3] http://doc.akka.io/docs/akka/snapshot/scala/fault-tolerance....
If the CPU fails, no one would say the program was unreliable.
In this case, the disk failed, because the antivirus unplugged it. Was the program unreliable?
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.
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?
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.
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".
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?
If you want nuanced dialog, start with nuance and make room for other people's opinions.
Things I did not say:
- It's reasonable for a program fault to reboot a computer.
- It's reasonable not to check error conditions.
- It's reasonable for a program to halt and catch fire.
I wish I were making up that last one, but I'm not. Here are some unreasonable quotes:
Think of your torrent software. If you crank your firewall to block it while it's running it will not crash. If your disk fills up it won't crash.
No one was saying it was okay for the program to crash.
'Halt and catch fire' is not generally considered a proportionate response
No one was advocating this.
I've no idea where you're getting this 'unplugged the disk' thing from, AV software does not work this way.
The AV software denied all disk I/O. If you have nowhere to put data, and no access to data, then you don't have a disk. You have a paperweight.
As for displaying random data, why would the programmer want to do this?
Obviously, the programmer did not "want" to do this. This is what happens when you try to do GPU programming and the I/O is suddenly cut. I've seen it, which is why I said it.
But your engines shutting down can be permanent or transient. Just like disk I/O failing.
The disk I/O didn't fail. It was completely cut off by the AV program. There was no chance of it resuming until the scan completed, which could take far longer than the 5 minutes required to reboot the computer.
Speaking of which, here's where that stupid "the program rebooted the computer" myth stemmed from:
According to one such report filed by Merge Healthcare in February, Merge Hemo suffered a mysterious crash right in the middle of a heart procedure when the screen went black and doctors had to reboot their computer.
To me, it sounds like they restarted the computer to get the AV program to stop. The program did not "crash so hard it rebooted the computer."
Here's how the program works:
Merge Hemo consists of two main modules. The main component is the actual medical device, connected to the catheters, through which data acquisition takes place. This component is connected to a local PC or tablets via a serial port.
The second component is a software package that runs on the doctor's computer or tablet and takes recorded data and logs it or displays it on the screen via simple-to-read charts.
So we see that the company does not have control over their environment. They have no say over what the doctor's computers are like. They have to live with the fact that the doctors' computers are running Windows, and that they run AV scans. It's not up to them.
This is important, because if the company had independently decided it was reasonable to deploy their software with an AV package, then the fault would lay with the company. But they didn't. Now, what can the company do?
Your point was that the software should behave gracefully in this environment. I agree; that was my point too.
The various people in this thread took what I said and morphed it into something so far from reality that I'm frankly a little worried that people are believing it. If I try to get a job, people might read this and conclude that I'm somehow advocating for 300-second crashes. Seriously?
My sole, singular point was this: Small programs are reliable programs. You can't have bugs in what you don't write.
That means a lot of things. But it does not mean "do not handle error conditions." I didn't even say that this program should exit. I said that the spectacular crash led to pinpointing the AV scan as the source of the issue.
I was called incompetent (indirectly), that my position was "extreme," and that I "denied all possibility of nuance." Ok. Sure.
I've re-read the entire article and this entire thread to double check myself and make sure that my assumptions are correct here, so if you see a mistake, please call it out with a quote.
I agree that I'm now being a little shall-we-say heated, and it's annoying that I'm now doing that because of how much I was provoked here. Actually, this is more amusing than annoying. If the whole world is claiming you came across poorly, then you came across poorly, regardless of what you think. I'm wondering where it all went wrong. So please, tell me: What aggression do you feel I started with? I'm genuinely hoping to learn here.
Isn't this all a little tedious? Why are we even doing this? Aren't there more interesting thoughts to think than litigating what someone did or didn't say? I don't know why this happened, and I don't know specifically what you want. But I'm open to suggestions.
Thank you for the advice. I appreciate it. Sorry for the sour grapes.
As I wrote in my other two posts tonight (more like morning, sigh) is that I tend to tune out emotional and aggressive writing styles. That's probably why my writing style tends to look aggressive. It's just the type of debates I tend to end up in (sigh, again).
So I apologize again if that got you upset at me.
AV software does not deny all disk IO. It just denies write access to a file very briefly and then goes on to the next file as the article stated it was a scheduled scan.
So you do have a disk but a few files temporarily can't be written to (still can be read). The program will get an error code from the write function and can just try to write again.
> The disk I/O didn't fail. It was completely cut off by the AV program. There was no chance of it resuming until the scan completed, which could take far longer than the 5 minutes required to reboot the computer.
This is where you are incorrect. And AV scan does not lock the entire disk for the duration of the scan. It locks and releases each file as it scans them. Fire up process monitor from sysinternals and look for yourself.
Tried it with my AV scanner with a manual scan. Looks like mine doesn't even do a lock on most of the files when doing a manual scan. So at most the file just couldn't be deleted.
> My sole, singular point was this: Small programs are reliable programs. You can't have bugs in what you don't write.
I pretty much agree with you on that one. Smaller programs are more reliable than larger programs.
> What aggression do you feel I started with? I'm genuinely hoping to learn here.
I found it humorous that you saw aggression in my words and that wpietri saw aggression in your words. Me, I just learned to tune out that sort of thing in other peoples posts.
> I said that the spectacular crash led to pinpointing the AV scan as the source of the issue.
And that's what I was arguing about in my original post. You know what Root Cause Analysis is? If not read up about it here: https://en.wikipedia.org/wiki/Root_cause_analysis
My argument was that while the crash identified the AV Scan as a causal factor, it wasn't the root cause. From the wikipedia article: "Though removing a causal factor can benefit an outcome, it does not prevent its recurrence within certainty."
The root cause was that the programmer didn't handle the error code that his file was locked. There are many more causal factors that can trigger the exact same outcome: indexing service, backup program, shadow copy, etc.
Unrelated to our debate, the medical company only blamed the AV software and the IT Staff. Not one mention that their program had a bug.
The fact that their release notes warned against AV software means that they knew their program was deficient. That's what really pisses me off.
A debate is by definition adversarial. I do tend to be more passionate when debating certain topics. If I've come across to you as aggressive I apologize. It's just my style of writing and you can freely ignore any aggression you see in it.
> > Only if the programmer or his management were incompetent
> This is just short of a personal attack, which is against the rules.
That comment wasn't about you so it can't be a personal attack against you. It was about a fictitious programmer and his fictitious management used in our examples.
Attacking what you've written is not a personal attack against you. I will rip your words apart, try to prove they are wrong, show where you've either made a faulty assumption or an error in logic. That's what a debate is.
I will never, ever under any circumstances attack you. If you can see that distinction I will gladly continue to debate with you.
This whole thing basically ballooned from this statement of yours:
> The antivirus basically unplugged the disk. What can it do to recover? There's nothing to be done.
Those are the words I'm challenging. You have two points there. The first is that the antivirus unplugged the disk. While I know you're not being literal you're not being accurate either. It locked one or more files.
The second was that there was nothing the program could have done. To this I gave an example of a program that does handle this exact situation and more.
From your other comment replying to someone else but still quoting me:
> > Think of your torrent software. If you crank your firewall to block it while it's running it will not crash. If your disk fills up it won't crash.
> No one was saying it was okay for the program to crash.
This is the example program I'm talking about. I wasn't implying that you think it was okay for the program to crash. I was giving you an example of a program that can handle disk and network error conditions without the need to restart itself (automatically or manually) nor crash itself or the system.
> 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.
I believe you in in that situation. GPUs have been designed with speed in mind and that makes for a very complex interface to them. But that reinforces a few arguments made by others in regards to this story, that being should medical equipment be using hardware not specifically designed for the purpose.
But going back to my comment of:
> > As for displaying random data, why would the programmer want to do this?
Based on your GPU comment above we may using different definitions of random data. I took your "random data" as "looks right on the screen but the numbers are wrong". If the programmer knows that his data source is temporarily unavailable, showing stale or corrupted data is the last thing he should do.
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.
Why is nobody questioning the propriety of using an off-the-shelf Windows PC in safety-of-life applications?
Agreed. So the app shouldn't contain anything extra not related to it's primary function.
However, handling error conditions reported by the operating trumps the extraneous code rule. But there are many ways to handle an error, including ignoring it if that's the proper thing to do.
Crashing is never the proper thing to do. If the program had simply exited at the very minimum, a restart would have taken a lot less time than a complete reboot of the machine. The software crashed that badly that it required a reboot of the machine.
> Why is nobody questioning the propriety of using an off-the-shelf Windows PC in safety-of-life applications?
They are, in the other threads. But using a better OS for the task wouldn't prevent the coding error the programmer did.
Let's say they chose Linux. A signal goes off or something else happens and their read call fails. Since they expect all their I/O to succeed they crash just like the Windows box.
If they bothered to handle the error and check for EINTR they'd know it was interrupted and not a hardware failure.
My point is, changing operating systems doesn't protect you from poorly coded applications.
No, that's a recipe for failure. Hardware will fail. Period.
Hoping that nothing will fail and therefore not taking steps to mitigate it is akin to designing cars not to crash. [0]
Failures need to be explicitly designed for and tested. It's truly depressing that companies where failure is fine (ex. Netflix's Chaos Monkey) understand this, while companies where failure is deadly don't.
But their app crashed. And hard. It required a machine reboot to restart. While it returned the machine to a known state it wasn't quick.
And in medical software, all code paths need to be tested.
The company claims that they included proper instructions in their documentation, advising companies to whitelist Merge Hemo's folders in order to prevent crashes from happening, so it seems that the whole incident was nothing more than an oversight on the medical unit's side."
Here's how I read that: The programmers of this piece of software assumed that some I/O operation would never fail and when it does the program shits itself. So instead of hardening their software to withstand loss of telemetry gracefully, which would cost time and money for the company, they just give instructions to disable scans on their folder.
Odds are good that somewhere this scan will happen (and it did). Either IT doesn't read the release notes or goofs the configuration or an antivirus update clears the white list. Might not even be the antivirus that interferes with the telemetry briefly.
But instead of having resilient software it's "the anitvirus software's fault" or "it's IT's fault" when something goes wrong because of their bad management/engineering decision.