I am working on a web assembly application in rust. The program relies on streaming a file and storing the data in memory. However I run into a rust_oom issue.
This issue only arises when recompiling the std library with atomic, bulk-memory, and mutable-global flags.
Reproducable via .cargo/config.toml:
[target.wasm32-unknown-unknown]
rustflags = ["-C", "target-feature=+atomics,+bulk-memory,+mutable-globals"]
[unstable]
build-std = ["panic_abort", "std"]
Compiling without these flags works fine.
The relevant rust code:
#[wasm_bindgen]
pub async fn start(r: JsValue) {
// javascript response into websys response
let resp: Response = r.dyn_into().unwrap();
// from example here https://github.com/MattiasBuelens/wasm-streams/blob/master/examples/fetch_as_stream.rs
let raw_body = resp.body().unwrap();
let body = ReadableStream::from_raw(raw_body.dyn_into().unwrap());
let mut stream = body.into_stream();
// store the data in memory
let mut v = vec![];
log("start streaming");
while let Some(Ok(chunk)) = stream.next().await {
//convert to vec<u8>
let mut x = chunk.dyn_ref::<Uint8Array>().unwrap().to_vec();
v.append(&mut x);
}
log(&format!("{}", v.len()));
log("done streaming");
}
The full error message provided
at rust_oom (wasm_memtest_bg.wasm:0xfa10)
at __rg_oom (wasm_memtest_bg.wasm:0xfdd4)
at __rust_alloc_error_handler (wasm_memtest_bg.wasm:0xfd38)
at alloc::alloc::handle_alloc_error::rt_error::hf991f317b52eeff2 (wasm_memtest_bg.wasm:0xfdb3)
at core::ops::function::FnOnce::call_once::ha90352dededaa31f (wasm_memtest_bg.wasm:0xfdc9)
at core::intrinsics::const_eval_select::h04f9b6091fe1f42f (wasm_memtest_bg.wasm:0xfdbe)
at alloc::alloc::handle_alloc_error::h82c7beb21e18f5f3 (wasm_memtest_bg.wasm:0xfda8)
at alloc::raw_vec::RawVec<T,A>::reserve::do_reserve_and_handle::h65538cba507bb5c9 (wasm_memtest_bg.wasm:0xc149)
at <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::he4014043296c78b9 (wasm_memtest_bg.wasm:0x1c85)
at wasm_bindgen_futures::task::multithread::Task::run::h77f1075b3537ddf9 (wasm_memtest_bg.wasm:0x5a0e)
Here is the full project if you want to test it out.
https://github.com/KivalM/memory-wasm
EDIT: The code required to reproduce the issue is provided in the first snippet. The full wasm application is provided in the repository so that you do not have to create one from scratch. I will include the rust code in the question.
The issue arises when loading a simple 500MB file into memory. Which should be possible via this approach. Yet Chrome(and chromium-based browsers) tend to run out of memory, whereas when the rustflags are not present the program runs just fine.
I will move the links here as they are not part of the question, but can be relevant.
https://rustwasm.github.io/2018/10/24/multithreading-rust-and-wasm.html
https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html
Related
I'm trying to build a system that is similar to FsBolero (TryWebassembly), Fable Repl and many more that uses Fsharp.Compiler.Services.
So I expect it is feasible to achieve my goals but I encountered a problem that I hope is only a result of my lack of experience with that realm of software development
I'm implementing a service that gives user the power to write custom algorithms (DSL) in the context of the domain system.
The code to compile come as a plain raw string that is fully correct F# code.
Sample DSL algorithm looks like:
let code = """
module M
open Lifespace
open Lifespace.LocationPricing
let alg (pricing:LocationPricing) =
let x=pricing.LocationComparisions.CityLevel.Transportation
(8.*x.PublicTransportationStation.Data+ x.RailwayStation.Data+ 5.*x.MunicipalBikeStation.Data) / 14.
"""
that code compiles correctly via CompileToDynamicAssembly. I also provided proper reference to my domain *.dll via -r Fsc parameter.
And here comes my problems as next I have the generated dynamic assembly and want to invoke that algorithm.
I do it with reflection (is there any other way?) with
f.Invoke(null, [|arg|]) when arg is of type LocationPricing and comes from main/hosting project reference.
The Invoke doesn't work because I have error:
Cannot cast LocationPricing to LocationPricing
I had the same problem when tried to use F# interactive services, the error was similar:
Cannot cast [A]LocationPricing to [B]LocationPricing
I'm aware I have two same dlls in the context and F# does have extern alias syntax to solve it.
But other mentioned public systems somehow deals with that or I'm doing it wrongly.
I will look at code of Bolero and FableRepl but it will definately take some time to understand the pitfalls.
Update: Full code (Azure Function)
namespace AzureFunctionFSharp
open System.IO
open System.Text
open Microsoft.Azure.WebJobs
open Microsoft.Azure.WebJobs.Extensions.Http
open Microsoft.AspNetCore.Http
open Microsoft.AspNetCore.Mvc
open Microsoft.Extensions.Logging
open FSharp.Compiler.SourceCodeServices
open Lifespace.LocationPricing
module UserCodeEval =
type CalculationResult = {
Value:float
}
type Error = {
Message:string
}
[<FunctionName("UserCodeEvalSampleLocation")>]
let Run([<HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)>] req: HttpRequest, log: ILogger , [<Blob("ranks/short-ranks.json", FileAccess.Read)>] myBlob:Stream)=
log.LogInformation("F# HTTP trigger function processed a request.")
// confirm valid domain dll location
// for a in System.AppDomain.CurrentDomain.GetAssemblies() do
// if a.FullName.Contains("wrometr.lam.to.ranks") then log.LogInformation(a.Location)
// let code = req.Query.["code"].ToString()
// replaced just to show how the user algorithm can looks like
let code =
"""
module M
open Lifespace
open Lifespace.LocationPricing
open Math.MyStatistics
open MathNet.Numerics.Statistics
let alg (pricing:LocationPricing) =
let x= pricing.LocationComparisions.CityLevel.Transportation
(8.*x.PublicTransportationStation.Data+ x.RailwayStation.Data+ 5.*x.MunicipalBikeStation.Data) / 14.
"""
use reader = new StreamReader(myBlob, Encoding.UTF8)
let content = reader.ReadToEnd()
let encode x = LocationPricingStore.DecodeArrayUnpack x
let pricings = encode content
let checker = FSharpChecker.Create()
let fn = Path.GetTempFileName()
let fn2 = Path.ChangeExtension(fn, ".fsx")
let fn3 = Path.ChangeExtension(fn, ".dll")
File.WriteAllText(fn2, code)
let errors, exitCode, dynAssembly =
checker.CompileToDynamicAssembly(
[|
"-o"; fn3;
"-a"; fn2
"-r";#"C:\Users\longer\azure.functions.compiler\bin\Debug\netstandard2.0\bin\MathNet.Numerics.dll"
"-r";#"C:\Users\longer\azure.functions.compiler\bin\Debug\netstandard2.0\bin\Thoth.Json.Net.dll"
// below is crucial and obtained with AppDomain resolution on top, comes as a project reference
"-r";#"C:\Users\longer\azure.functions.compiler\bin\Debug\netstandard2.0\bin\wrometr.lam.to.ranks.dll"
|], execute=None)
|> Async.RunSynchronously
let assembly = dynAssembly.Value
// get one item to test the user algorithm works in the funtion context
let arg = pricings.[0].Data.[0]
let result =
match assembly.GetTypes() |> Array.tryFind (fun t -> t.Name = "M") with
| Some moduleType ->
moduleType.GetMethods()
|> Array.tryFind (fun f -> f.Name = "alg")
|>
function
| Some f -> f.Invoke(null, [|arg|]) |> unbox<float>
| None -> failwith "Function `f` not found"
| None -> failwith "Module `M` not found"
// end of azure function, not important in the problem context
let res = req.HttpContext.Response
match String.length code with
| 0 ->
res.StatusCode <- 400
ObjectResult({ Message = "No Good, Please provide valid encoded user code"})
| _ ->
res.StatusCode <-200
ObjectResult({ Value = result})
**Update: changing data flow **
To move forward I resigned to use domain types in both places. Instead I do all logic in domain assembly and only pass primitives (strings) to reflected invocation. I'm also suprised a lot that caching still works everytime I do compilation on each Azure Function call. I will experiment as well with FSI, in theory it should be faster than reflection but with additional burden to pass parameters to evaluations
In your example, the code that runs inside your dynamically compiled assembly and the code calling it need to share a type LocationPricing. The error you are seeing typically means that you somehow ended up with different assembly loaded in the process that is calling the dynamically compiled code and the code actually running the computation.
It is hard to say exactly why this happened, but you should be able to check whether this is indeed the case by looking at assemblies loaded in the current App Domain. Say that your shared assembly is MyAssembly. You can run:
for a in System.AppDomain.CurrentDomain.GetAssemblies() do
if a.FullName.Contains("MyAssembly") then printfn "%s" a.Location
If you were using F# Interactive Services, then a trick to fix this is to start an FSI session and then send an interaction to the service that loads the assembly from the right place. Something along those lines:
let myAsm = System.AppDomain.CurrentDomain.GetAssemblies() |> Seq.find (fun asm ->
asm.FullName.Contains("MyAssembly"))
fsi.EvalInteraction(sprintf "#r #\"%s\"" myAsm.Location)
In WebGL we have special extension EXT_disjoint_timer_query for proper GPU profiling, but I can't find good manual how to use it. For example initialization below works in my machine
let gl = canvas.getContext('webgl');
let ext = gl.getExtension('EXT_disjoint_timer_query');
let startQuery = ext.createQueryEXT();
ext.queryCounterEXT(startQuery, ext.TIMESTAMP_EXT);
But last line return undefined. Also I am inspired from source example in regl library, but it's too sophisticated.
I need to download HTML code from some web page. What is the best way to approach this task? As I understand there are very few working web frameworks for Rust right now and hyper is the one most people use? But after searching it's documentation I couldn't find a way. The closest I got is this
extern crate hyper;
use hyper::Client;
fn main() {
let client = Client::new();
let res = client.get("http://www.bloomberg.com/")
.send()
.unwrap();
println!("{:?}", res);
}
But it returns Response, which doesn't seem to contain any code from HTML body.
Note: this answer is outdated!
I don't have the time to update this with every hyper release. But please see my answer to a very related question: How can I download a website's content into a string?
It's a bit hidden: The Response type implements the trait Read. One method of Read is read_to_string which reads everything into the a String. That's a simple way you can get the body.
extern crate hyper;
use hyper::Client;
use std::io::Read;
fn main() {
let client = Client::new();
let mut res = client.get("http://www.bloomberg.com/")
.send()
.unwrap();
let mut body = String::new();
res.read_to_string(&mut body).expect("failed to read into string");
println!("{}", body);
}
Currently Rustdoc (the HTML documentation of Rust) is a little bit misleading because Rust beginners think that trait implementations don't add any important functionality. This is not true, so better look out for it. However, the hyper documentation could be better...
I notice that Rust's test has a benchmark mode that will measure execution time in ns/iter, but I could not find a way to measure memory usage.
How would I implement such a benchmark? Let us assume for the moment that I only care about heap memory at the moment (though stack usage would also certainly be interesting).
Edit: I found this issue which asks for the exact same thing.
You can use the jemalloc allocator to print the allocation statistics. For example,
Cargo.toml:
[package]
name = "stackoverflow-30869007"
version = "0.1.0"
edition = "2018"
[dependencies]
jemallocator = "0.5"
jemalloc-sys = {version = "0.5", features = ["stats"]}
libc = "0.2"
src/main.rs:
use libc::{c_char, c_void};
use std::ptr::{null, null_mut};
#[global_allocator]
static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
extern "C" fn write_cb(_: *mut c_void, message: *const c_char) {
print!("{}", String::from_utf8_lossy(unsafe {
std::ffi::CStr::from_ptr(message as *const i8).to_bytes()
}));
}
fn mem_print() {
unsafe { jemalloc_sys::malloc_stats_print(Some(write_cb), null_mut(), null()) }
}
fn main() {
mem_print();
let _heap = Vec::<u8>::with_capacity (1024 * 128);
mem_print();
}
In a single-threaded program that should allow you to get a good measurement of how much memory a structure takes. Just print the statistics before the structure is created and after and calculate the difference.
(The "total:" of "allocated" in particular.)
You can also use Valgrind (Massif) to get the heap profile. It works just like with any other C program. Make sure you have debug symbols enabled in the executable (e.g. using debug build or custom Cargo configuration). You can use, say, http://massiftool.sourceforge.net/ to analyse the generated heap profile.
(I verified this to work on Debian Jessie, in a different setting your mileage may vary).
(In order to use Rust with Valgrind you'll probably have to switch back to the system allocator).
P.S. There is now also a better DHAT.
jemalloc can be told to dump a memory profile. You can probably do this with the Rust FFI but I haven't investigated this route.
As far as measuring data structure sizes is concerned, this can be done fairly easily through the use of traits and a small compiler plugin. Nicholas Nethercote in his article Measuring data structure sizes: Firefox (C++) vs. Servo (Rust) demonstrates how it works in Servo; it boils down to adding #[derive(HeapSizeOf)] (or occasionally a manual implementation) to each type you care about. This is a good way of allowing precise checking of where memory is going, too; it is, however, comparatively intrusive as it requires changes to be made in the first place, where something like jemalloc’s print_stats() doesn’t. Still, for good and precise measurements, it’s a sound approach.
Currently, the only way to get allocation information is the alloc::heap::stats_print(); method (behind #![feature(alloc)]), which calls jemalloc's print_stats().
I'll update this answer with further information once I have learned what the output means.
(Note that I'm not going to accept this answer, so if someone comes up with a better solution...)
Now there is jemalloc_ctl crate which provides convenient safe typed API. Add it to your Cargo.toml:
[dependencies]
jemalloc-ctl = "0.3"
jemallocator = "0.3"
Then configure jemalloc to be global allocator and use methods from jemalloc_ctl::stats module:
jemalloc_ctl::stats::allocated
jemalloc_ctl::stats::resident
Here is official example:
use std::thread;
use std::time::Duration;
use jemalloc_ctl::{stats, epoch};
#[global_allocator]
static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
fn main() {
loop {
// many statistics are cached and only updated when the epoch is advanced.
epoch::advance().unwrap();
let allocated = stats::allocated::read().unwrap();
let resident = stats::resident::read().unwrap();
println!("{} bytes allocated/{} bytes resident", allocated, resident);
thread::sleep(Duration::from_secs(10));
}
}
There's a neat little solution someone put together here: https://github.com/discordance/trallocator/blob/master/src/lib.rs
use std::alloc::{GlobalAlloc, Layout};
use std::sync::atomic::{AtomicU64, Ordering};
pub struct Trallocator<A: GlobalAlloc>(pub A, AtomicU64);
unsafe impl<A: GlobalAlloc> GlobalAlloc for Trallocator<A> {
unsafe fn alloc(&self, l: Layout) -> *mut u8 {
self.1.fetch_add(l.size() as u64, Ordering::SeqCst);
self.0.alloc(l)
}
unsafe fn dealloc(&self, ptr: *mut u8, l: Layout) {
self.0.dealloc(ptr, l);
self.1.fetch_sub(l.size() as u64, Ordering::SeqCst);
}
}
impl<A: GlobalAlloc> Trallocator<A> {
pub const fn new(a: A) -> Self {
Trallocator(a, AtomicU64::new(0))
}
pub fn reset(&self) {
self.1.store(0, Ordering::SeqCst);
}
pub fn get(&self) -> u64 {
self.1.load(Ordering::SeqCst)
}
}
Usage: (from: https://www.reddit.com/r/rust/comments/8z83wc/comment/e2h4dp9)
// needed for Trallocator struct (as written, anyway)
#![feature(integer_atomics, const_fn_trait_bound)]
use std::alloc::System;
#[global_allocator]
static GLOBAL: Trallocator<System> = Trallocator::new(System);
fn main() {
GLOBAL.reset();
println!("memory used: {} bytes", GLOBAL.get());
{
let mut vec = vec![1, 2, 3, 4];
for i in 5..20 {
vec.push(i);
println!("memory used: {} bytes", GLOBAL.get());
}
for v in vec {
println!("{}", v);
}
}
// For some reason this does not print zero =/
println!("memory used: {} bytes", GLOBAL.get());
}
I've just started using it, and it seems to work well! Straight-forward, realtime, requires no external packages, and doesn't require changing your base memory allocator.
It's also nice that, because it's intercepting the allocate/deallocate calls, you should be able to add custom logic if desired (eg. if memory usage goes above X, print the stack-trace to see what's triggering the allocations) -- although I haven't tried this yet.
I also haven't yet tested to see how much overhead this approach adds. If someone does a test for this, let me know!
I'm trying to use async workflows in F# to fetch several web requests.
However, some of my requests are occasionally returning errors (e.g. http 500), and I don't know how to handle this. It appears like my F# program gets stuck in an infinite loop when running in the debugger.
I'm probably missing some stuff, cause examples I seen didn't compile out of the box. First thing I found that helped was this bit of code:
type System.Net.WebRequest with
member req.GetResponseAsync() =
Async.BuildPrimitive(req.BeginGetResponse, req.EndGetResponse)
and then I have my bit of code to fetch the requests, which is pretty standard from examples I've seen:
let async_value = async {
let req = WebRequest.Create(url)
let! rsp = req.GetResponseAsync()
return (rsp :?> HttpWebResponse).StatusCode
}
and then I try to get the result:
let status = Async.RunSynchronously(async_value)
But when I run my program in debugger, it breaks at req.EndGetResponse because server returned internal server error 500. If I keep just continuing execution, it gets in a funky loop, breaking at req.EndGetResponse (sometimes several in a row), and at let status = Async.RunSynchronously(async_value).
How do I get around the exception problem so I can get my status code? Also, do I need the type thing I did above? Or am I missing some library/dll for F#/VS 2010 Beta 1, of which this is already a part of?
I actually run several requests in parallel, using Async.RunSynchronously(Async.Parallel(my_array_of_async_values)), though I don't think that is related to the exception issue I'm having.
The fact the examples I've come across only use Async.Run rather than Async.RunSynchronously is probably an indicator I'm missing something... =/
It's now called 'AsyncGetResponse' (no longer 'GetResponseAsync'). And 'Run' was renamed to 'RunSynchronously'. So I don't think you're missing anything substantial here, just name changes in the latest release.
What are your debugger settings with regard to "Tools\Options\Debugging\General\Enable Just My Code" and "Debug\Exceptions" (e.g. set to break when any first-chance CLR exception is thrown or not)? I am unclear if your question involves the program behavior, or the VS tooling behavior (sounds like the latter). This is further confounded by the fact that breakpoint/debugging 'locations' in F# Beta1 have some bugs, especially regarding async workflows, which means that the behavior you see in the debugger may look a little strange even if the program is executing properly...
Are you using VS2008 CTP or VS2010 Beta1?
In any case, it appears the exception due to a 500 response is expected, this is how WebRequest works. Here's a short demo program:
open System
open System.ServiceModel
open System.ServiceModel.Web
[<ServiceContract>]
type IMyContract =
[<OperationContract>]
[<WebGet(UriTemplate="/Returns500")>]
abstract Returns500 : unit -> unit
[<OperationContract>]
[<WebGet(UriTemplate="/Returns201")>]
abstract Returns201 : unit -> unit
type MyService() =
interface IMyContract with
member this.Returns500() =
WebOperationContext.Current.OutgoingResponse.StatusCode <-
System.Net.HttpStatusCode.InternalServerError
member this.Returns201() =
WebOperationContext.Current.OutgoingResponse.StatusCode <-
System.Net.HttpStatusCode.Created
let addr = "http://localhost/MyService"
let host = new WebServiceHost(typeof<MyService>, new Uri(addr))
host.AddServiceEndpoint(typeof<IMyContract>, new WebHttpBinding(), "") |> ignore
host.Open()
open System.Net
let url500 = "http://localhost/MyService/Returns500"
let url201 = "http://localhost/MyService/Returns201"
let async_value (url:string) =
async {
let req = WebRequest.Create(url)
let! rsp = req.AsyncGetResponse()
return (rsp :?> HttpWebResponse).StatusCode
}
let status = Async.RunSynchronously(async_value url201)
printfn "%A" status
try
let status = Async.RunSynchronously(async_value url500)
printfn "%A" status
with e ->
printfn "%s" (e.ToString())
You can use try...with inside the async to catch exceptions:
let async_value =
async {
let req = WebRequest.Create("http://unknown")
try
let! resp = req.AsyncGetResponse()
return "success"
with
| :? WebException as e -> return "failure"
}