Waiting for a message in a thread

[boutell]

An interesting library. Have you found a way for a thread to wait for a message while in the middle of a function? Rather than returning from it and waiting for onmessage to be called?

Without that, it seems like the operations that currently must be asynchronous, such as AJAX calls, pretty much still must be, which eliminates a lot of the benefit.

Of course even if it were available we'd still be doing a lot of inefficient JSON-ification just to escape that...

[keithwhor]

I'm not sure what you're asking specifically, can you clarify? With an example perhaps?

[boutell]

When I hear "threads," I think of being able to do this:

var thing = goGetTheThingThatTakesALongTime();
thing.useTheThingWhichAlsoTakesALongTime();

Simple, synchronous logic like this is normally impossible in JavaScript because it is single-threaded, so everything must be asynchronous, whether via callbacks, promises or the new "async" keyword.

[boutell]

... When I first saw webworkers, I thought "hey, you could use message passing to implement a synchronous API."

But then I realized that "onmessage" is asynchronous, so... you can't really.

If there was a way to wait for a message in a thread:

function goGetTheThingThatTakesALongTime() {
sendMessage('goGetTheThing');
var response = waitForMessage();
return response;
}

Then you could implement synchronous APIs with it, but there isn't one.

I admit though that even if it worked, it would still be a real drag on performance, because message passing between threads is done with strings.