Calling websocket->close() and websocket->write() from another thread

[ludekvodicka]

Sorry for bothering again. I have another crash on Win64 but I'm not sure if this is a bug or wrong library usage.

Should it be safe to call websocket->close() from another thread (or websocket->write()) ?

Occasionally the application is crashing after calling websocket->close() from the main application thread (when simulating manual client disconnection in our tests).

It's because s->context is 0xddddddddddd during TopicTree::unsubscribeAll()

But I'm not sure if this is a bug or it's caused by calling it from the other thread because this code https://github.com/uNetworking/uSockets/blob/master/src/socket.c#L65 doesn't seem to thread-safe.

Is there any list of methods that are safe to call from another thread?

And is there any "writeable" callback in the uWebsockets thread where is it possible to run these not thread-safe methods? I read about us_timer_set which should be probably utilized too (https://github.com/uNetworking/uWebSockets/blob/master/examples/UpgradeAsync.cpp)

Thank you

[ludekvodicka]

I just find that also calling us_listen_socket_close from the main thread is occasionally crashing the app.

[hst-m]

Have you read user manual regarding threads? https://github.com/uNetworking/uWebSockets/blob/master/misc/READMORE.md

[ludekvodicka]

I read it several times but based on your reply I probably missed something.

I know a whole uWS::App has to run in own thread. But I didn't find any example/mention in the docs how to invoke commands (finalize loop, send data,...) from other threads.

I'm aware that all these issues are caused probably by missing synchronization, but I didn't find any way how to invoke it from the uWS::App thread. This is the reason why I'm posting it here.

Should I use a timer for such cases? Or is there any "Writeable" callback where I can execute it?

Thanks for pointing me to any example/docs.

[ludekvodicka]

It seems I found the solution in uWS::Loop::get() and uWS::Loop::defer(), but I'm not sure if this is currently the recommended way, because there is no mention of this anywhere in the documentation or examples.

[ghost]

Loop defer is the only thread safe function.

[ludekvodicka]

Thanks for the confirmation and for the great library.

If I can suggest, it would be probably good to have any example or mention about defer in the documentation.

[jrch2k20]

Yeah, i would appreciate an example on how to use uWS::SSLApp::Publish from another thread.

[ghost]

If you search in Discussions you'll find 5 answers of this

[jrch2k20]

I literally just got mind blown that there is a discussion tab on github LOL, sry i'll check there now.

100% my bad

[ghost]

Hehe np, maybe I should link to it from the readme. It's a new tab

[jrch2k20]

yeah i think would be nice, good stuff in there and yeah defer and publish working like a charm now ;)

Awesome work and tyvm for your time