> I'm not sure I understand how emscripten_set_main_loop() will help my JavaScript execute the async code... are you saying that the compiled code in each thread is blocking the JavaScript code?
Yes, see https://emscripten.org/docs/porting/emscripten-runtime-environment.html?#browser-main-loop if you have a "while (1)" loop as in the example there, then it never exits back to the JS event loop. All execution has to stop for that to happen. That's the same on the main thread and on workers, and the solution can be the same, as described there. About Asyncify: I think most of your worries are not an issue (it works with pthreads, and you can implement multiple async events at once, but you need to add a little JS layer yourself to multiplex them, etc.). But if you can just switch to using emscripten_set_main_loop() or some other async way of doing your main loop, that would be much simpler and much better. On Wed, Mar 25, 2020 at 5:51 PM Kevin McGrath <[email protected]> wrote: > Ah! Thanks for the details! I looked into Asyncify and ruled it out > because of this from the emscripten documentation: > > It is not safe to start an async operation while another is already >> running. The first must complete before the second begins. > > > That would mean one HTTP request at a time, one after another, and any > time we want to use Asyncify for any other async JavaScript tasks we may > run into trouble that would be a nightmare to debug. Plus there's more > issues described in that doc, such as if we get an event (like a keypress) > while the async JavaScript is running it doesn't sound too stable when it > calls into compiled code. Lastly, they mention that you should always run > optimized builds if you're using Asyncify, which will not be fun to debug. > Taking all of that into consideration, it didn't sound like a good option > to me, especially since I wasn't sure it would work in the first place with > USE_PTHREADS=1. > > I'm not sure I understand how emscripten_set_main_loop() will help my > JavaScript execute the async code... are you saying that the compiled code > in each thread is blocking the JavaScript code? > > Sorry for so many questions, I'm very new to JavaScript and know very > little about its internal workings. Also seems impossible to Google for > this kind of stuff. > > Thank you! > > > On Wednesday, March 25, 2020 at 4:39:29 PM UTC-7, Alon Zakai wrote: >> >> emscripten_thread_sleep() will check the pthread event queue, which means >> it can receive C messages from other threads - those are synchronized using >> shared memory. However, it can't help with JS events, as to get those to >> happen you need to actually return to the main JS event loop. The browser >> won't run those events otherwise. >> >> To do that, you can use Asyncify ( >> https://emscripten.org/docs/porting/asyncify.html) and >> emscripten_sleep(). Or, you can manually return to the main event loop >> yourself, replacing an infinite event loop with an >> emscripten_set_main_loop() etc. >> >> On Wed, Mar 25, 2020 at 1:56 PM Kevin McGrath <[email protected]> >> wrote: >> >>> Hello! >>> >>> I'm hoping someone has already run into this before and can tell me what >>> I'm doing wrong... >>> >>> I have a JavaScript function I'm calling from a C++ multi-threaded game >>> that is designed to perform an async HTTP fetch. >>> >>> I'm building the game using USE_PTHREADS=1 and PROXY_TO_PTHREAD=1 and >>> I've tried both having the JavaScript function embedded in a EM_JS() and in >>> a --js-library. The C++ code sparks off a pthread and calls into the >>> JavaScript function, and that JavaScript code executes and then returns >>> back to the C++ code. What doesn't work is any of the Promise / await >>> code, nothing is executing in those code blocks. >>> >>> I've tried calling emscripten_thread_sleep() from the C++ code, which is >>> still executing in the thread waiting on the JavaScript asynchronous code >>> to call it back, it just never happens. The network request is just marked >>> as "(pending)" in Chrome and never changes. >>> >>> So my question is, what's the right way to run Promise/async/await code >>> in a WebAssembly pthread/Web Worker? >>> >>> Thank you!! >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "emscripten-discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/emscripten-discuss/aecd43c5-6662-4d7d-bb8c-15461e75522e%40googlegroups.com >>> <https://groups.google.com/d/msgid/emscripten-discuss/aecd43c5-6662-4d7d-bb8c-15461e75522e%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/emscripten-discuss/fe4d60af-6a74-40e6-b37f-31a04eb34afd%40googlegroups.com > <https://groups.google.com/d/msgid/emscripten-discuss/fe4d60af-6a74-40e6-b37f-31a04eb34afd%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. 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