Theme using emscripten

Question

I am trying to use thread with Emscripten and I do not understand how it works. I read some text about web workers, and I'm not sure I understood.

When I look in the tests folder, I see the pthread stuff .

I use "std :: thread" and got the following error:

unresolved symbol: pthread_create 

Should I use web workers instead of the default thread?

Thanks!

Answer 1

Pthread support is added and can already be used with a small amount of settings. Since std :: thread uses pthread under the hood, you can also use it. See this discussion for more information.

What I had to do:

• Use new emscripten (I am testing with 1.34.1)
• Install Firefox at night
• Enable flag USE_PTHREADS
• Remember that this is experimental, and some things are finishing in nature.

I had a problem writing a pthread example that actually ran, but here's the code using std :: thread, which demonstrates the basic functionality that worked for me:

 // main.cpp #include <thread> #include <iostream> void func() { std::cout << "I'm a thread!\n"; } int main() { std::thread test1(func); std::thread test2(func); std::thread test3(func); // join seems to lock up the browser //test1.join(); //test2.join(); //test3.join(); } 

I managed to use threads in a larger project (for a larger one for posting here!), So they are viable. I’m afraid it’s not so fast, although it may improve over time.

To build it:

emcc main.cpp -o main.html -s USE_PTHREADS = 1 --std = C ++ 11

Output in Firefox Nightly 42.0a1 (2015-07-16):

Preliminary allocation of 1 worker for pthread breed pool.
Preliminary allocation of 1 employee for the pthread pool pool.
Preliminary allocation of 1 employee for the pthread pool pool.
I am a thread! I am a thread! I am a thread!

Answer 2

Unfortunately, multithreaded code cannot be compiled using Emscripten. Web site workers can be calculated at the same time, but they cannot maintain general state and therefore cannot replace threads.

See: http://kripken.imtqy.com/emscripten-site/docs/porting/guidelines/portability_guidelines.html

Change Since others have a pointer, Emscripten is moving forward with my original answer and now has experimental support for pthreads (and most likely soon for C ++ inline threads) https://groups.google.com/forum/#!topic/emscripten -discuss / gQQRjajQ6iY