Description

Potential deadlock in EventIPCTransport.DispatchWailsEvent
(transport_event_ipc.go)

We hit a deadlock that traces back to a lock ordering
issue in the Wails event dispatch path.

In transport_event_ipc.go:7-17, DispatchWailsEvent acquires
windowsLock.RLock() and then calls window.DispatchWailsEvent() for each
window — which calls ExecJS → InvokeSync, blocking until the main
thread executes the JS.

func (t *EventIPCTransport) DispatchWailsEvent(event *CustomEvent) {
     t.app.windowsLock.RLock()          // holds read lock
     defer t.app.windowsLock.RUnlock()
     for _, window := range t.app.windows {
         if event.IsCancelled() {
             return
         }
         window.DispatchWailsEvent(event)  // → ExecJS → InvokeSync
 (blocks on main thread)
     }
 }

If the main thread needs windowsLock for any reason (e.g.
processURLRequest → WindowManager.GetByID → RLock, or any write lock
from NewWithOptions/Remove), you get a deadlock:

• Event dispatch goroutines: hold windowsLock.RLock(), waiting for main
  thread via InvokeSync
• Main thread: waiting for windowsLock (blocked because a write lock is
  pending, which blocks behind the active readers)

In our case this froze the entire app for 4+ hours. We confirmed the
deadlock via pprof goroutine dump — goroutine 1 (main thread) blocked
on windowsLock.RLock for 261 minutes, with ~30 event dispatch
goroutines piled up behind it.

Would it be possible to snapshot the window list under the lock and
then release it before calling InvokeSync? Something like:

func (t *EventIPCTransport) DispatchWailsEvent(event *CustomEvent) {
    t.app.windowsLock.RLock()
    snapshot := make([]Window, 0, len(t.app.windows))
    for _, w := range t.app.windows {
        snapshot = append(snapshot, w)
    }
    t.app.windowsLock.RUnlock()

    for _, window := range snapshot {
        if event.IsCancelled() {
            return
        }
        window.DispatchWailsEvent(event)
    }
}

This is on Wails v3 alpha.74, macOS (darwin/arm64).

To Reproduce

...

Expected behaviour

...

Screenshots

No response

Attempted Fixes

No response

System Details

...

Additional context

No response