Is there anyone successfully using URLSession tasks on Windows VM?

ShikiSuen · August 5, 2024, 6:48am

I have written the following two SPM using URLSession to fetch remote data:

This is how I use the URLSession API:

pizza-studio/EnkaDBGenerator/blob/1e09ad861f075af4c371c9322d958b6d8ff3dbd3/Sources/EnkaDBGeneratorModule/DimbreathModels/DimModelsEnumProtocol.swift#L34-L61


      
          static func getDataStack1By1<T: DimModelsEnumProtocol>() async throws -> [T: Data] {
              var resultBuffer = [T: Data]()
              for currentCase in T.allCases {
                  resultBuffer[currentCase] = try await currentCase.rawDataToParse()
              }
              return resultBuffer
          }
          
          static func getDataStack<T: DimModelsEnumProtocol>(oneByOne: Bool = false) async throws -> [T: Data] {
              guard !oneByOne else { return try await getDataStack1By1() }
              return try await withThrowingTaskGroup(
                  of: (tag: T, data: Data).self,
                  returning: [T: Data].self
              ) { taskGroup in
                  T.allCases.forEach { currentCase in
                      taskGroup.addTask {
                          let data = try await currentCase.rawDataToParse()
                          return (tag: currentCase, data: data)
                      }
                  }

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github.com

pizza-studio/EnkaDBGenerator/blob/1e09ad861f075af4c371c9322d958b6d8ff3dbd3/Sources/EnkaDBGeneratorModule/DimbreathModels/DimModelsEnumProtocol.swift#L27-L31


      
          func rawDataToParse() async throws -> Data {
              print("// Fetching: \(jsonURL.absoluteString)")
              let (data, _) = try await URLSession.shared.asyncData(from: jsonURL)
              return data
          }

github.com

pizza-studio/EnkaDBGenerator/blob/07f3d67b5f866a1acfb18ea017fd2cfc27eacde3/Sources/EnkaDBGeneratorModule/FoundationImpl/FoundationImpl.swift#L24-L57


      
          /// A reimplementation of `URLSession.shared.asyncData(from: url)` required for Linux
          ///
          /// ref: https://gist.github.com/aronbudinszky/66cdb71d734ae48a2609c7f2c094a02d
          ///
          /// - Parameter url: The URL for which to load data.
          /// - Returns: Data and response.
          ///
          /// - Usage:
          ///
          ///     let (data, response) = try await URLSession.shared.asyncData(from: url)
          func asyncData(from url: URL) async throws -> (Data, URLResponse) {
              guard !isWindows else {
                  return try await data(from: url)
              }
              return try await withCheckedThrowingContinuation { continuation in
                  let task = self.dataTask(with: url) { data, response, error in
                      if let error = error {
                          continuation.resume(throwing: error)
                          return
                      }

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They work fine on Linux and Apple systems.
However, they both fail on Windows.
As soon as the URLSession start retrieving remote data, the application immediately terminates with no error message generated.

// The July (1st half) 2024 snapshot build of Swift 6 and the Swift 5.10.1 stable build are both tried in this case. The July (2nd half) snapshot is unusable on Windows due to lack of a DLL.

I wonder what is happening with Swift Foundation URLSession on Windows.

ShikiSuen · August 5, 2024, 8:54am

Update: This issue does not exist on a physical Windows machine.

It seems a compatibility issue between Swift Foundation and VMware Fusion (intel).

compnerd · August 5, 2024, 4:57pm

If you have a simple standalone test case that demonstrates the issue, it might still be worth filing an issue on swift-foundation so that this can be looked into.

CC: @Tony_Parker @jmschonfeld @icharleshu

jmschonfeld · August 5, 2024, 5:00pm

Yep, we'd definitely appreciate an issue filed on the repo so we can track this! It would also be helpful to know if this reproduces in both older (<=5.10) toolchains in addition to Swift 6/main or just one or the other. We recently overhauled swift-corelibs-foundation (where FoundationNetworking lives) and while the source code didn't change all too much for FoundationNetworking, it changed a bit as well as the build configuration so if this is only an issue in Swift 6 it could be a regression caused by the restructuring.

cc @jrflat

ShikiSuen · August 6, 2024, 1:43pm

I believe that this gist is already enough for testing:

gist.github.com

https://gist.github.com/aronbudinszky/66cdb71d734ae48a2609c7f2c094a02d

URLSession+async.swift

import Foundation
#if canImport(FoundationNetworking)
import FoundationNetworking
#endif

/// Defines the possible errors
public enum URLSessionAsyncErrors: Error {
    case invalidUrlResponse, missingResponseData
}

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jrflat · August 8, 2024, 9:19pm

Including the above gist,

let (data, response) = try! await URLSession.shared.asyncData(from: URL(string: "http://example.com/")!)

works as expected on my Parallels Desktop Windows VM for ARM using both Swift 5.10.1 and 6.0. (I was also running into the DLL issues you mentioned earlier, but today's 6.0 toolchain build seems to be working for me.)

Perhaps the issue is Intel- or VMware Fusion-specific. I'll try to reproduce with an Intel setup to see if we can gather more info.