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Comment by mwexler | Hacker News Reader

firefoxatemyram.com is still available. Perhaps we can put a site up there as well.

Yep, firefox is currently 555 MB resident and using 1.5 GIGABYTES of virtual memory space. Goddamn, firefox, you are a pig. Saddest thing? I've got gmail, github, and maybe 10 static pages open.

Linux just looks like it ate your RAM. Firefox straight up does eat it.

Am I missing something? Does Firefox not use unused RAM for cache in a similar manner as Linux uses unused RAM?

555 MB is still a lot. That's the actual memory usage.

Modern web browser are complicated pieces of software that are also the nexus for most people's interactions with their computer. tiles' point is correct: Firefox will tend to cache things much like the OS itself. We should expect it to use a lot of memory. If your system performance has not suffered, there is no problem.

Performance does suffer, because the operating system doesn't know that all that memory being used by firefox is just cache. And firefox doesn't know when the operating system would like to use memory for something other than cache. So when you start a second large program, it's thrashing time.

VMs like vmware have the exact same problem, where the host might want memory used by the guest, and you end up with weird scenarios where the guest's swap is in the host's disk cache, but the guest's memory is in the host's swap. One of the things guest tools are supposed to do is communicate with the host regarding memory pressure. Firefox lacks this feedback mechanism.

I'm sorry, but this reply doesn't make any sense to me. If applications have to cache something, they should use the file system, which would not affect their resident memory at all. Maybe I'm just old school, but where I come from operating systems handle the memory hierarchy, not applications.

They cache it in memory to avoid latency. Writing to and reading from disk increases latency. Even crossing the kernel boundary will increase latency.

Modern web browsers have architectures similar to OSes at this point - because they have requirements similar to OSes. I think it's natural that they will take on some of the same responsibilities.

If it's cached to the filesystem, it'll be handled by the file cache, under the kernel's control with the rest of RAM. Maybe browser makers have a good reason for thinking they can do better than the OS, I don't know, but having two systems trying to do the same job with the same resources sounds like a recipe for instability and inefficiency to me.

If you have to cross the kernel boundary every time you want to access something in your cache, your "cache" is now much, much slower. Note that this applies even if the OS keeps the file in memory, and doesn't require going to disk.

Sure, but if accepting that cache slowdown makes the rest of the system more responsive and more useful for background tasks, it may be worthwhile. It's a trade-off, and the browser makers have every incentive to be as selfish as possible.

Where I come from, what you're describing is called pre-fetching, not caching. That's why your earlier comment confused me.

No, I'm talking about caching: keeping data around that you have previously used, assuming you will use it again. However, in order to support caching, you must pre-allocate memory.

I suspect you don't know what virtual memory is: http://news.ycombinator.com/item?id=3699481

Yes, I know what virtual memory is, I'm a computer engineer and I work on operating systems. I'm just extremely impressed that they needed 1.5 GB of address space, for christ's sake.

Insert here some pithy comment about Apollo missions and Twitter, or whatever.

The reason I suspected that is grabbing 1.5 GB of virtual memory doesn't mean much. It just means you asked the OS to change its book-keeping to allow you to access that much. Applications and libraries that aggressively cache and prefetch routinely do that sort of thing.

The reason for acquiring a lot of virtual memory is to save memory and improve performance.

Why is Firefox always mentioned in this context? Sure they have had a history of it, but lately they've been fine and if one compares the combined spawned processes of Chrome, Chrome typically has more memory consumption.

I keep my Firefox up to date with release versions, have few plugins, and still find it absorbing memory at a tremendous rate. Chrome can also use memory, but somehow manages to let it go sometimes, as well as not drag my entire (Windows) system to a stutter.

I guess so many of us mention FF in this context because it still happens to us, even though we gamely continue to use it. But we still love it, and that's why we continue to use it. Though admittedly, most of us have a Chrome on the side...

The ongoing efforts of the MemShrink project keep finding memory leaks -- usually in Firefox addons. You can read more about it at http://blog.mozilla.com/nnethercote/category/memshrink/

Remember that when you are accounting for those you also need to remove all of the stuff that is paged into every process and is the same across them, such as shared libraries and the like. Most likely Chrome is using less ram than you think.

Chrome has a built-in task manager that takes this into account, as well as a slightly more hidden "Stats for nerds" link in the task manager that gives total memory usage. It's just genuinely very memory hungry once you add up all its processes.

HN's pro-Google bias.

What does about:memory say?

Basically the same thing. It's been several hours, right now it says it has 644 MB of explicit allocations, it is 675 MB resident, and has 1,633 MB of virtual address space. When I looked at about:memory right after composing my original post, the numbers were within a few megabytes of what htop reported.

Putting that in Chrome gets me to a page that was new to me, chrome://memory-redirect/

I never knew this existed...thanks for pointing this out.

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