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Does memory leak? (1995)

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Re: Does memory leak? (1995)

#111

Post by mehrdadn »

derefr wrote: post #53
chapium wrote: post #16

Earlier quoted context omitted.

This is clearly not my subject area. Why would we be spawning processes for HTTP requests? This sounds awful for performance. My best guess is a security guarantee.

Not spawning, forking. Web servers were simple “accept(2) then fork(2)” loops for a long time. This is, for example, how inetd(8) works. Later, servers like Apache were optimized to “prefork” (i.e. to maintain a set of idle processes waiting for work, that would exit after a single request.) Long-running worker threads came a long time later, and were indeed intensely criticized from a security perspective at the tim…

Thanks for that last paragraph, I'd never thought about that aspect of processes. Learned something new today.

Re: Does memory leak? (1995)

#112

Post by saagarjha »

asdfasgasdgasdg wrote: post #107
saagarjha wrote: post #89

Earlier quoted context omitted.

I'm pointing out that an arena is more about "a region of memory that you can split up to use later" than "a region of memory that must be allocated and deallocated all at once".

I've never heard that use of the term "arena". Are you thinking of slabs? Arenas are typically allocated and deallocated at once. That's their main feature.

https://sourceware.org/glibc/wiki/MallocInternals#Arenas_and...

Re: Does memory leak? (1995)

#113

Post by 2OEH8eoCRo0 »

jakeinspace wrote: post #69

As somebody working on embedded software for aerospace, I'm surprised this missile system even had dynamic memory allocation. My entire organization keeps flight-critical code fully statically allocated.

This right here. My previous job was in defense and although it was not an embedded project all the software architects on the project were embedded guys used to doing things their way. Dynamic allocation was strictly forbidden.

Re: Does memory leak? (1995)

#114

Post by emsy »

harryf wrote: post #108
emsy wrote: post #50

Earlier quoted context omitted.

No, they did what good engineers do: They analyzed the problem and found a feasible and robust solution. Following rules without thinking is not what good programmers do. I’d argue that most problems of modern software development stem from this mindset, even when it’s a rule that should be applied 99% of the time.

All good until years later, a new team builds, unaware of the leak, same system into a longer range missile...

Right, but that doesn’t invalidate the previous decisions made at that time. And it’s not only a problem in software. Accidents can happen because engineers trade material strength to reduce weight only to find out that over a number of generations they slowly crept above the safety margin that was decide upon 10 years ago, resulting in catastrophic failure. I’m sorry I don’t have the actual story at hand right now, but it’s not unimaginable either way. The problem you described has more to do with proper passing of knowledge and understanding of existing systems rather than strictly adhering to a fixed set of best practices.

Re: Does memory leak? (1995)

#115

Post by dahart »

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 had a family friend who worked on missiles and drones and other defense systems. He was really one of my dad’s running buddies, and he was a super nice guy, had 4 kids, went to church, etc.

One day, I believe during the Iraq occupation, maybe ~12 or 13 years ago, I asked him very directly how he felt about working on these killing machines and whether it bothered him. He smiled and asked if I’d rather have the war here in the U.S.. He also told me he feels like he’s saving lives by being able to so directly target the political enemies, without as much collateral damage as in the past. New technology, he truly believed was preventing innocent civilians from being killed.

It certainly made me think about it, and maybe appreciate somewhat the perspective of people who end up working on war technology, even if I wouldn’t do it. This point of view assumes we’re going to have a war anyway, and no doubt the ideal is just not to have wars, so maybe there’s some rationalization, but OTOH maybe he’s right that he is helping to make the best of a bad situation and saving lives compared to what might happen otherwise.

Re: Does memory leak? (1995)

#118

Post by Dylan16807 »

ncmncm wrote: post #109
wbhart wrote: post #77

Earlier quoted context omitted.

Right, but that isn't the argument that was being used here, which is my point. The way I read it, the contractor cared only enough to get the design over the line so the customer would sign off on it. Their argument was that you shouldn't care about leaks due to scheduled deconstruction, not because of a technical consideration. There exist options between no reclaim and using a garbage collector which could be cons…

Fetishism is not compatible with sound engineering. "Cared only enough" is just your projection. The contractor knew the requirements, and satified the requirements with no waste of engineering time, and no risk of memory reclamation interfering with correct operation. The person complaining about leaks wasted both his time and the contractor's.

You had a good comment going until the last sentence.

When your job is performing an analysis of the code, five minutes asking for a dangerous feature to be justified is ridiculously far from a "waste of time".

Re: Does memory leak? (1995)

#119

Post by kebman »

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…

Oh, I'm sure you'd make a killing! :D <3

Re: Does memory leak? (1995)

#120

Post by throwaway462564 »

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…

> First, I logically agreed that the missiles were supporting our armed services and I believed that our government was generally on the right side of history and needed the best technology to continue defending our freedoms

I hope you are not writing about the US government. I don‘t think the US military can be described as protecting our freedoms after interfering and starting wars all over the world in the past. We are sadly mostly the aggressors and not the defendants.

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