Thread is not working in WebAssembly export

[stubbsy345]

Operating system or device, Godot version, GPU Model and driver (if graphics related):
Godot alpha 2 Webassembly export.

Thread does not work in WebAssembly, I am conscious that may be because it is not possible to thread on this medium. But can't find anything stating that.

var thread = Thread.new()
func start_order(ord):
	thread.start(self, "add_order", ord)
	
func add_order(ord):
	ordered = {"ReturnTime": ord["returnTime"], "WaitLeft": ord["returnTime"]}
	print(ordered)
	thread.wait_to_finish()

Works fine when not using a thread in webassembly.

[akien-mga]

cc @eska014

[leonkrause]

Threads are not in the WASM spec yet, work is ongoing here: https://github.com/webassembly/threads

[stubbsy345]

Is there any way of getting similar functionality to threading. I'm trying to avoid HTTP requests from blocking the main thread?

[reduz]

you could write a module that uses a javascript worker natively

…

On Mon, Nov 6, 2017 at 10:51 AM, stubbsy345 ***@***.***> wrote: Is there any way of getting similar functionality to threading. I'm trying to avoid HTTP requests from blocking the main thread? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#12699 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AF-Z20ELN8NMzqcT3TnVU-zjxnnOINXgks5szw77gaJpZM4QTGbf> .

[Zylann]

In the meantime, I'm pretty sure I've seen a way to use HttpClient without blocking the main thread. Then you woudln't need to use a thread. The doc example shows how to do it with polling: http://docs.godotengine.org/en/latest/learning/features/networking/http_client_class.html?highlight=HttpClient
Except you would use _process instead of a while loop and a sleep ;)

[blockspacer]

Modern Chrome supports threads & "Shared Array Buffer" by default ( https://developers.google.com/web/updates/2018/10/wasm-threads )
For other browsers: you can enable threads with flags / browser settings. See also "Shared Array Buffer" support ( https://caniuse.com/#feat=sharedarraybuffer )
You can enable threads with USE_PTHREADS emscripten flag ( https://emscripten.org/docs/porting/pthreads.html ) and detect threads support at runtime (need to add 2 separate build modes: with and without threads, as fallback).

NOTE: when using USE_PTHREADS don`t block main loop, prefer emscripten_run_in_main_loop/thread emscripten-core/emscripten#7535
Very usefull to read: emscripten-core/emscripten#7535 and emscripten-core/emscripten#8325

  # avoid having main thread synchronously block on a pthread
  # (the ".. sync blocking on main thread is bad.." mantra),
  # so dropping the pthread_join()
  # (and ensuring NO_EXIT_RUNTIME so runtime stays alive)
  # should also avoid the hang
  # DOM operations can only be done on the main thread
  # That includes things like printing to the console (!!!),
  # and even things like XMLHttpRequests!

[KoBeWi]

Can anyone still reproduce this bug in Godot 3.2.3 or any later release?

[Calinou]

@KoBeWi Yes, as HTML5 thread support isn't implemented in a stable Godot release yet. Browser support for WebAssembly threads is still not fully reliable yet either, especially on mobile platforms.

[akien-mga]

Well this is fixed, threads are supported and working in HTML5 with a custom build (threads=yes).

3.2.4 will probably ship with both thread and no-thread templates to select at export.

[lenscas]

I just gave https://godotengine.org/article/dev-snapshot-godot-3-2-4-beta-3 a try to see how it works and I'm not sure how to enable threads?

I don't see an option for it in the export though. Do I need to do something special, am I blind or something else?

[Faless]

@lenscas as @akien-mga mentioned, thread support requires a custom build for now.
The option has not yet been added to the export UI, but assuming you compiled a template with threads_enabled=yes and you use that as a custom template it will work.
The stable 3.2.4 will likely ship both templates, and add the option to the export dialog

[blackears]

I'm using stable 3.4 and still running into the same issue. Threads for web are not enabled automatically and I cannot find any option for it in the export options either.

[Calinou]

I'm using stable 3.4 and still running into the same issue. Threads for web are not enabled automatically and I cannot find any option for it in the export options either.

Threads still need to be enabled on export by changing Export Type in the HTML5 export preset:

See Exporting for the web as for why HTML5 threads are disabled by default.

Using both threads and GDNative at the same time may be supported in a future release, but 3.4.x doesn't support that.

[blackears]

When I select that option, I am given an error that a necessary export template is not available. I opened the Manage Export Templates window, but the webassembly_threads is not there. I did download what was presented, but it did not make this error message go away.

[akien-mga]

Mono templates can't be built with threading support sadly. It's available for non-Mono builds. Likewise for GDNative support

Also, thus issue dates back to before threading support was even implemented. Please open new issues when so many years have passed.

[blackears]

I came to this thread from #34506 which was referencing this as a solution for C# threading issues. I'm basically just looking for a way to use async/await in C# and export something that works for web.

[Faless]

@blackears as I mentioned in #34506 (comment) the mono version do not support threads, because the mono version we use do not support modern emscripten versions.
Godot 4 should should come with donet6 which should support modern emscripten versions (and thus threading).

[ashelleyPurdue]

@blackears as I mentioned in #34506 (comment) the mono version do not support threads, because the mono version we use do not support modern emscripten versions. Godot 4 should should come with donet6 which should support modern emscripten versions (and thus threading).

Why does Godot offer an option if that option isn't real?

[Zireael07]

@ashelleyPurdue There are a LOT of things that do NOT work in some combination of export platform/renderers