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Does memory leak? (1995)

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Re: Does memory leak? (1995)

#281

Post by DagAgren »

colonCapitalDee wrote: post #252
pietrovismara wrote: post #55

Earlier quoted context omitted.

Have you watched Minority Report? What could go wrong with preemptively punishing crimes!

This is a strawman. Nobody uses missiles for law enforcement, the very idea is ridiculous. Presumably the > person who intends to kill you in this context is a terrorist hiding a cave somewhere, or a certain Iranian general. Now, it's definitely debatable if those striking those targets is morally correct (and I usually don't believe that it is), but it's silly to equate a military strike with the type of law enforce…

A "terrorist hiding in a cave" is the actual strawman here.

Re: Does memory leak? (1995)

#282

Post by mannykannot »

jldugger wrote: post #280
mannykannot wrote: post #248

Earlier quoted context omitted.

It is not just a heuristic if you have hard upper bounds on the things that matter - in that case, it is static analysis. A missile has a limited, and well-defined, fuel supply. In the case of memory management, it is not enough to just free it after use; you need to ensure that you have sufficient contiguous memory for each allocation. If you decide to go with a memory-compaction scheme, you have to be sure it never…

This depends entirely on the mode of operation which I suspect neither of us know in great detail; if in any circumstance the runtime of the program is not tied to expenditure of fuel you have literal ticking time bomb. Ideally we'd be able to tie such assertions into a unified static analysis tool, rather than having humans evaluate conflicting analyses. And god forbid the hardware parameters ever change, because no…

Well, yes, I already explained that it depended on circumstances, and just let me add that I would bet the engineer quoted in the article (explaining that the memory leaks were a non-issue) knew much more about the specifics than either of us.

The Ariane 5 issue is not, of course, a memory leak or other rescource-release-and-reuse issue. It is a cautionary tale about assumptions (such as the article's authors assumption that memory leaks are always bad.)

Re: Does memory leak? (1995)

#283

Post by jldugger »

andreareina wrote: post #47

"Git is a really great set of commands and it does things like malloc(); malloc(); malloc(); exit();" https://www.youtube.com/watch?v=dBSHLb1B8sw&t=113

And that really bit hard when you wanted to start running git webservers. All the lib code was designed to exit upon completion with no GC, and now you're running multiple read queries per second with no free(). oops.

Re: Does memory leak? (1995)

#284

Post by kragen »

imtringued wrote: post #269
kragen wrote: post #151

Earlier quoted context omitted.

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…

Real weapons are not like that. They are expensive, they can fail to kill their target and they can also cause collateral damage. If death notes were as easy to obtain as guns there would clearly be an increase in homicides but that's not true with military missiles. The Slaughterbots video is absolutely awful. First of all quadrocopters have an incredibly small payload capacity and limited flight time. A quadrocopte…

Before you had posted your comment, I had already explained in https://news.ycombinator.com/item?id=22394213 why everything in it is wrong, except for the first line.

As for the first line, you assert that real weapons are expensive, unreliable, and kill unintended people. Except in a de minimis sense, none of these are true of knives. Moreover, you seem to be reasoning on the basis of the premise that future technology is not meaningfully different from current technology.

In conclusion, your comment consists entirely of wishful and uninformed thinking.

Re: Does memory leak? (1995)

#285

Post by Someone »

hinkley wrote: post #139
monocasa wrote: post #132

Earlier quoted context omitted.

So I kind of disagree with the idea that arenas are all about deallocation at once. There's other contexts where you have separate arenas but don't plan on deallocating in blocks, mainly around when you have memory with different underlying semantics. "This block of memory is faster, but not coherent and needs to be manually flushed for DMA", "this block of memory is fastest but just not DMA capable at all", "there's…

I can’t remember the last time I read C code, but I do recall a particular time when I was reading a library that had been written with a great deal of attention to reliability. The first thing it did was allocate enough memory for the shutdown operations. That way on a malloc() failure, it could still do a a completely orderly shutdown. Or never start in the first place. From that standpoint, you could also categori…

That strategy is more important on systems that don’t do demand paged virtual memory. In Think Class Library on classic Mac OS, it was called the “Rainy day fund”.

One can also do that in stages:

- allocate a large block at startup

- when running out of memory, reallocate it at a smaller size and warn the user

- when running out of memory again, free the block and attempt an orderly shutdown.

Re: Does memory leak? (1995)

#286

Post by Someone »

MaxBarraclough wrote: post #140
monocasa wrote: post #132

Earlier quoted context omitted.

So I kind of disagree with the idea that arenas are all about deallocation at once. There's other contexts where you have separate arenas but don't plan on deallocating in blocks, mainly around when you have memory with different underlying semantics. "This block of memory is faster, but not coherent and needs to be manually flushed for DMA", "this block of memory is fastest but just not DMA capable at all", "there's…

Those aren't arenas. I'm inclined to agree with Wikipedia's definition, which does emphasise deallocation all at once: > A region, also called a zone, arena, area, or memory context, is a collection of allocated objects that can be efficiently deallocated all at once.

can be efficiently deallocated all at once.

There are implementations of arenas that, basically, act as separate memory managers. You can allocate and free memory inside them at will, but can also deallocate the whole thing in one sweep. The latter can be a lot faster, but of course, it requires you to know you can throw away all that memory in one go (handling web requests is the exemplar use case)

Re: Does memory leak? (1995)

#287

Post by colonCapitalDee »

DagAgren wrote: post #281
colonCapitalDee wrote: post #252

Earlier quoted context omitted.

This is a strawman. Nobody uses missiles for law enforcement, the very idea is ridiculous. Presumably the > person who intends to kill you in this context is a terrorist hiding a cave somewhere, or a certain Iranian general. Now, it's definitely debatable if those striking those targets is morally correct (and I usually don't believe that it is), but it's silly to equate a military strike with the type of law enforce…

A "terrorist hiding in a cave" is the actual strawman here.

Uhh who do you think missiles are usually launched at?

Re: Does memory leak? (1995)

#288

Post by DagAgren »

colonCapitalDee wrote: post #287
DagAgren wrote: post #281

Earlier quoted context omitted.

A "terrorist hiding in a cave" is the actual strawman here.

Uhh who do you think missiles are usually launched at?

People going about their lives just like you and me, surrounded by other people, mostly.

They may be terrorists, but that does not make their daily lives much different to ours.

Re: Does memory leak? (1995)

#289

Post by cushychicken »

TedDoesntTalk wrote: post #146
cushychicken wrote: post #57

Earlier quoted context omitted.

I recently interviewed, and was offered a job at, Draper Labs in Cambridge MA. The technical work was super interesting. Everyone I spoke to was plainly super sharp, and not morally bankrupt. I fielded similar moral concerns as you, but truthfully, I don't really have much of a personal ethical problem with it. I was a little more concerned at having to explain it to all of my friends, many of whom are substantially…

First time I’ve heard of someone accepting or not accepting a job based on peer perception. Maybe you should re-evaluate who your peers are if they can’t accept you for your career choices?

That's a pretty reductive and reactionary comment, and I feel like I'm succumbing to some of my worst impulses by responding to it four days later. But, clearly, some point in there has touched a nerve, so here goes:

For one thing: it missed (or ignored, but I'll default to "missed") my point about the large pay cut involved.

For another: it stack ranked peer perception as being more important in my decisionmaking than the pay cut. My original comment certainly appears to value perception over pay. That's a huge miscommunication of my priorities, and my fault. I wasn't about to take a 30% pay cut. The fact that I'd also have to withstand the negative scrutiny of my friends and family just made it that much easier to decline.

For a third: we all hope to do work that we can be proud of. Part of that pride is to be able to hold up the fruits of our labor to others and take pride in having participated in it. I don't think I could have done that without thinking twice had I taken that job - and I'm not just talking about the security clearance angle here. Dealing with the negative reactions from my friends and family would have been a problem for me. Not the biggest one, but a problem. Acceptance is a big precursor to feeling safe, and self actualized. I feel the acceptance of a group of peers now. I do not want to trade that for more intellectually challenging work with an ethical component that my friends and family find questionable. I'd apply this reasoning in equal part to a role where I was paid more, but just as questionable. (I don't want to get rich building technology that enables the next Bernie Madoff, for example.)

Perhaps I'm of a weaker intellectual constitution than you are to be so easily influenced by the opinion of other people. However, I view that mental flexibility as a strength. I also trust the opinion (and, by extension, the underlying moral character) of my peers, who have been a positive moral force in my life. Hence, it was important to me not to compromise their trust and acceptance of me, and my career choices.

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