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Does memory leak? (1995)

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Re: Does memory leak? (1995)

#181

Post by spencerwgreene »

amw-zero wrote: post #106
rowanG077 wrote: post #97

Earlier quoted context omitted.

I find it interesting that such critical code is written in C. Why not use something with a lot more (easily)statically provable properties. Like Rust or Agda?

You’ll find that for very serious, industrial applications, a conservative mindset prevails. C may not be trendy at the moment, but it powers the computing world. Its shortcomings are also extremely well known and also statically analyzable. Also, think about when flight software started being written. Was Rust an option? And once it came out, do you expect that programmers who are responsible for millions of people’…

> I can’t think of anything more important or critical than software that runs on a commercial airplane.

Nuclear reactors?

Re: Does memory leak? (1995)

#182

Post by tomcam »

GordonS wrote: post #42

A bit OT, but I wonder how I'd feel if I was offered a job working on software for missiles. I'm sure the technical challenge would be immensely interesting, and I could tell myself that I cared more about accuracy and correctness than other potential hires... but from a moral standpoint, I don't think I could bring myself to do it. I realise of course that the military uses all sorts of software, including line of b…

I mean all due respect with this question. Not an attack. Do you think your country should have such missiles? If not, how would you handle the defense case in which your country is attacked but does not have them? Also note that most of Europe is defended by these missiles made in the USA.

Re: Does memory leak? (1995)

#183

Post by tomcam »

jmpman wrote: post #71
GordonS wrote: post #42

A bit OT, but I wonder how I'd feel if I was offered a job working on software for missiles. I'm sure the technical challenge would be immensely interesting, and I could tell myself that I cared more about accuracy and correctness than other potential hires... but from a moral standpoint, I don't think I could bring myself to do it. I realise of course that the military uses all sorts of software, including line of b…

Straight out of college, I was offered a job writing software for missiles. Extremely interesting area, working for my adjunct professor’s team, who I highly admired and whose class was the best of my college career. The pay was on par with all my other offers. I didn’t accept for two reasons. First, I logically agreed that the missiles were supporting our armed services and I believed that our government was general…

Thank you for a nuanced and very well explained set of reasons. This is a difficult subject to handle dispassionately here and you did an admirable job.

Re: Does memory leak? (1995)

#184

Post by anarazel »

mannykannot wrote: post #31
simias wrote: post #13

I think it's a bad mindset to leak resources even when it doesn't effectively matter. In non-garbage collected languages especially, because it's important to keep in mind who owns what and for how long. It also makes refactoring easier because leaked resources effectively become some sort of implicit global state you need to keep track of. If a function that was originally called only once at startup is not called r…

I think you are conflating two issues: while one should understand who owns what and for how long, it does not follow that one should always free resources even when it is not necessary, if doing so adds complexity and therefore more things to go wrong, or if it makes things slower than optimal. In this particular case, correctness was not primarily assured by a massive amount of testing (though that may have been do…

Freeing memory also isn't free - the bookkeeping necessary, both at allocation and at free time and potentially also for the allocating code has costs.

In postgres memory contexts are used extensively to manage allocations. And in quite few places we intentionally don't do individual frees, but reset the context as a whole (freeing the memory). Obviously only where the total amount of memory is limited...

Re: Does memory leak? (1995)

#185

Post by 3pt14159 »

kragen wrote: post #151
3pt14159 wrote: post #133

Earlier quoted context omitted.

It's a valid question, but realistically if Costa Rica were invaded a number of countries would step in to help them. I love Costa Rica, it's one of the most beautiful countries I've been to and I do appreciate the political statement their making, but at the same time they're in a pretty unique situation. As for the ethics of working on weapons, I think there is a lot of grey when it comes to software. It tends to c…

In the last 40 years, Panama and Grenada were invaded, Honduras had a coup, Colombia had a civil war, Venezuela is currently having a sort of civil war, Nicaragua's government was overthrown by a foreign-armed terrorist campaign, and El Salvador's government sent death squads out to kill its subjects. Nobody stepped in to help any of them except Colombia. Why would Costa Rica be different? > Would I work on software…

Eh, there is a difference between the examples you've sited and Costa Rica. They're an ally of the US and a strong democracy focussed on tourism.

> The logical extreme of this is Death Note

I don't really deal with logical extremes. It leads to weird philosophies like Objectivism or Stalinism. In international relations terms, I'm a liberal with a dash of realism and constructivism. I don't live in my ideal world. My ideal world doesn't have torture or murder or war of any kind. It doesn't have extreme wealth inequality or poverty. Unless this is all merely a simulation, I live in the real world. Who has the power to kill people? Lots of people. Everyone driving a car or carrying a gun. Billions of people. It's a matter of degree and targeting and justification and blow-back and economics and ethics and so many other things that it's not really sensible to talk about it.

I'm familiar with the arguments against AI being used on the battlefield, but even though I abhor war, I'm not convinced that there should be a ban.

Re: Does memory leak? (1995)

#186

Post by anarazel »

H8crilA wrote: post #26
ptero wrote: post #23

Earlier quoted context omitted.

In a perfect world, yes. But in a hard real time system (and much of missile control will likely be designed as such), timing may be the #1 focus. That is, making sure that events are handled in at most X microseconds or N CPU cycles. In such cases adding GC may open a new can of worms. I agree that in general leaking resources is bad, but sometimes it is good enough by a large margin. Just a guess.

It would be an acceptable solution if the memory supply would vastly outsize the demand, by over an order of magnitude. For example if the program never needed more than 100MiB and you'd install 1GiB or 10GiB. 10GiB is still nothing compared to the cost of the missile, and you get the benefit of truly never worrying about the memory management latency. My favorite trick to optimizing some systems is to see if I can m…

One TB of memory is actually quite expensive. And uses a fair bit of power.

Re: Does memory leak? (1995)

#187

Post by jmpman »

prostheticvamp wrote: post #167
Razengan wrote: post #93

Earlier quoted context omitted.

> he pulled me aside and sternly instructed “You should never repeat that story” We really need more exposure for the things that people like that want to silence..

He wasn’t silencing anyone. There were no black suits with billy clubs outside. He was warning the kid that if he went around repeating that aloud he’d burn himself on the interview trail as someone too naive to tow the corporate line and likely to reveal embarrassing workplace details to outsiders. He was doing the naive youngster a favor, before he could hurt his own career. The use of the phrase “people like that”…

Nah, I was smarter than that. I already had multiple offers, and had no intention of working for a government contractor. I mostly wanted to see how this recruiter would react to my flippant statement. If he had vehemently defended his company, it would have implied that the whole government contracting wasn’t quite as disfunctional as I’d experienced. His reaction basically confirmed my suspicions. It was a “don’t talk too loud about what we all know is going on”, along with a “how dare you unmask us”. Sure, it was also a “holy hell, you can’t talk to recruiters like that”.

But, no black suits with billy clubs.

And, I’m not suggesting that anything was out of norm for any of these government contractors. They’re delivering a very specialized service with immense regulations. There are very few companies which can produce the same product, so the competition is low and the feedback loop in procurement cycles is much longer.

Re: Does memory leak? (1995)

#189

Post by p1esk »

kragen wrote: post #175
dahart wrote: post #160

Earlier quoted context omitted.

> The logical extreme of this [...] Is that your ideal world? Clearly not. Would you please not post an extreme straw-man and turn this into polarizing ideological judgement? The post you’re responding to very clearly agreed that war is morally questionable, and very clearly argued for middle ground or better, not going to some extreme. You don’t have to agree with war or endorse any kind of killing in any way to see…

You assert that "software that does a better job of, say, facial recognition to lessen the likelihood of a predator drone killing an innocent civilian" is "middle ground", "not going to some extreme", "trying to prevent damage", and "nuanced". It is none of those. It is a non-nuanced extreme that is going to cause damage and kill those of us in the middle ground. Reducing it to a comic book is a way to cut through th…

What's your moral stance on developing defense mechanisms against Slaughterbot attacks? What if the best defense mechanism is killing the ones launching the attacks?

Re: Does memory leak? (1995)

#190

Post by GordonS »

tomcam wrote: post #182
GordonS wrote: post #42

A bit OT, but I wonder how I'd feel if I was offered a job working on software for missiles. I'm sure the technical challenge would be immensely interesting, and I could tell myself that I cared more about accuracy and correctness than other potential hires... but from a moral standpoint, I don't think I could bring myself to do it. I realise of course that the military uses all sorts of software, including line of b…

I mean all due respect with this question. Not an attack. Do you think your country should have such missiles? If not, how would you handle the defense case in which your country is attacked but does not have them? Also note that most of Europe is defended by these missiles made in the USA.

I've mentioned this a few times already in other comments, but I'd be in much less of a quandry about missiles used for defense purposes. Especially so if they could only be used for shooting down other missiles.
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