molten crescent
im reading and parsing a bunch of .txt files, nothing crazy. no unsafe involved. my program has already exited, but RAM usage is still through the roof, without taskmanager or resource monitor showing which process is holding it (see images). any ideas whats going on here?
pure snow
even if you had a memory leak the memory should be freed on program exit
molten crescent
yeah thats what confuses me
i know i can just reboot and that will most likely fix it, but i'd like to actually figure out whats going on
sand birch
Any chance it's just the file cache, meaning it will get evicted as soon as any process needs memory?
balmy steeple
lol sweatremoval
sand birch
lol sweatremoval
Pretty sure it's just cache
molten crescent
but how can 1.5gb of files cause 30gb of ram usage?
like even if it held literally everything in ram that wouldnt even come close
im suspecting rust-analyzer
pure snow
but how can 1.5gb of files cause 30gb of ram usage?
well, try the allocation first
molten crescent
will a simple vec![0u8; 10_000_000_000] suffice?
pure snow
sure yeah
pure snow
right, well you can try using them
balmy steeple
add a sleep() after it and black_box it
molten crescent
i tried mutating it with indices i input with stdin
fn main() {
let mut x = vec![0_u8; 10_000_000_000];
loop {
let mut s = String::new();
std::io::stdin().read_line(&mut s).unwrap();
let i = s.trim_end().parse::<usize>().unwrap();
x[i] = 42;
let mut s = String::new();
std::io::stdin().read_line(&mut s).unwrap();
let i = s.trim_end().parse::<usize>().unwrap();
println!("{}", x[i]);
}
}
dunno what that is, but im on a fresh windows 11 install
fresh as in 1 day old
closed everything:
still over 26gb occupied
and the code i posted earlier supposedly uses 300kb only
ooh its using virtual memory
sand birch
Oh, yeah, you'll have to actually use each memory page in order to have them in RAM
sand birch
A loop would help
molten crescent
fn main() {
let mut x = vec![0_u8; 10_000_000_000];
for i in 0..x.len() {
x[i] = (i % 256) as _;
}
loop {
let i = read_input();
x[i] = read_input() as _;
let i = read_input();
println!("{}", x[i]);
}
}
fn read_input() -> usize {
let mut buf_string = String::new();
std::io::stdin()
.read_line(&mut buf_string)
.unwrap();
buf_string
.trim_end()
.parse()
.unwrap()
}
now it shows up properly
but it seems to struggle to acquire the memory
i'd expect to be able to start inputting stuff after a few seconds at most
but after a minute it still didnt let me
so i assume its constantly swapping pages?
sand birch
I mean, it's not surprising your computer would struggle to free up 10 GB of RAM on your whim
molten crescent
really? i thought the whole point of RAM is exactly that
sand birch
If a process has recently written to RAM, the OS has to write that page to disk before assigning it to you. If you do that for 10 000 000 pages, that takes a while.
molten crescent
im not an expert, but i feel like this would kinda defeat the point of having ram in the first place
could you try the code yourself and tell me how it performs on your machine?
sand birch
Yours isn't the only process that uses RAM.
molten crescent
so what
sand birch
But anyways, it does appear not all of the 10 GB you decided to take up for yourself was file cache or already commited pages.
What you could try is to keep allocating RAM until it takes more than one second to perform a write, and then immediately quit.
molten crescent
i've let it run for a while now, and my entire system started lagging
until i eventually got this
and shouldnt exiting the process free up all the memory?
sand birch
It should free up the process's private memory. It may not free up the files that the process read.
molten crescent
but again, its just 1.5gb of files, nowhere near enough to explain the 20+ im looking at
molten crescent
my target is 3.2gb
idk i find it hard to believe that this is normal
RAMMap64 from sysinternals
interesting that it says 11gb is unused
i dont really know what any of this means, just throwing stuff out here
sand birch
Well it seems your memory cleaner did clean your memory...
molten crescent
except that task manager still reports 99% usage
sand birch
ruby salmon
closed everything:
Do you happen to have wsl?
molten crescent
Do you happen to have wsl?
its installed (for docker desktop), but i havent used it yet
ruby salmon
You can disregard me then
molten crescent
as expected, the problem was gone after the reboot, so i dont think we'll ever figure out what it was
ruby salmon
wsl just has the possibility to eat memory that windows can't see