Understanding the onmessage event and the event loop

[allsey87]

As I understand, once we call into the Emscripten binary via main (or dynCall_ii for a thread), the event loop is blocked unless we unwind using Asyncify.

Despite this, it seems that even after rewinding, my main worker is able to receive checkMailbox messages from other threads without any problems. How is this possible if the event loop of the main worker is blocked?

[allsey87]

Never mind, I see now that _asyncify_start_unwind is being reassigned in it's body which tripped up my analysis and caused me to miss that module was being unwound.