Hi, I have a little concurrency problem. Seems that my Go-wasm-defined event handlers run concurrently instead of synchronously.
Basically, the event handler is called by runtime.handleEvent which calls into the syscall/js defined version of it Link to source <https://cs.opensource.google/go/go/+/master:src/runtime/lock_js.go;l=244?q=handlEeVE&sq=&ss=go%2Fgo:src%2Fruntime%2F> // handleEvent gets invoked on a call from JavaScript into Go. It calls the event handler of the syscall/js package // and then parks the handler goroutine to allow other goroutines to run before giving execution back to JavaScript. // When no other goroutine is awake any more, beforeIdle resumes the handler goroutine. Now that the same goroutine // is running as was running when the call came in from JavaScript, execution can be safely passed back to JavaScript. func handleEvent() { e := &event{ gp: getg(), returned: false, } events = append(events, e) *eventHandler() // !!!!* clearIdleID() // wait until all goroutines are idle e.returned = true gopark(nil, nil, waitReasonZero, traceEvNone, 1) events[len(events)-1] = nil events = events[:len(events)-1] // return execution to JavaScript pause(getcallersp() - 16) } In syscall/js, Link to source <https://cs.opensource.google/go/go/+/master:src/syscall/js/func.go;l=69?q=handleEve&sq=&ss=go%2Fgo> func handleEvent() { cb := jsGo.Get("_pendingEvent") if cb.IsNull() { return } jsGo.Set("_pendingEvent", Null()) id := uint32(cb.Get("id").Int()) if id == 0 { // zero indicates deadlock select {} } funcsMu.Lock() f, ok := funcs[id] funcsMu.Unlock() if !ok { Global().Get("console").Call("error", "call to released function") return } this := cb.Get("this") argsObj := cb.Get("args") args := make([]Value, argsObj.Length()) for i := range args { args[i] = argsObj.Index(i) } *result := f(this, args) // My callback runs here* cb.Set("result", result) } Basically, f causes a deadlock because it locks a mutex but never unlocks before being called again in response to another JS event. If I remove the lock, it's fine but he program should be incorrect as event handlers should be run synchronously. *Tried to instrument the code to display the call stack. You can see toward the end that there is an attempt to take a lock while handling the focus event that has not been unlocked beforehand while processing the click event.* 2022/08/05 22:24:25 focusTodo-App wasm_exec.js:22 2022/08/05 22:24:25 LOCKING ==================================================================== wasm_exec.js:22 2022/08/05 22:24:25 LOCkED ---------------------------------------------------------------------- wasm_exec.js:22 2022/08/05 22:24:25 6 wasm_exec.js:22 runtime.Callers wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.SDEBUG wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1 wasm_exec.js:22 syscall/js.handleEvent wasm_exec.js:22 runtime.handleEvent wasm_exec.js:22 runtime.goexit wasm_exec.js:22 2022/08/05 22:24:25 UNLOCKING ==================================================================== wasm_exec.js:22 2022/08/05 22:24:25 7 wasm_exec.js:22 runtime.Callers wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.SDEBUG wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.freelock wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1 wasm_exec.js:22 syscall/js.handleEvent wasm_exec.js:22 runtime.handleEvent wasm_exec.js:22 runtime.goexit wasm_exec.js:22 2022/08/05 22:24:25 UNLOCkED ---------------------------------------------------------------------- wasm_exec.js:22 2022/08/05 22:24:32 focusTodo-App wasm_exec.js:22 2022/08/05 22:24:32 LOCKING ==================================================================== wasm_exec.js:22 2022/08/05 22:24:32 LOCkED ---------------------------------------------------------------------- wasm_exec.js:22 2022/08/05 22:24:32 6 wasm_exec.js:22 runtime.Callers wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.SDEBUG wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1 wasm_exec.js:22 syscall/js.handleEvent wasm_exec.js:22 runtime.handleEvent wasm_exec.js:22 runtime.goexit wasm_exec.js:22 2022/08/05 22:24:32 UNLOCKING ==================================================================== wasm_exec.js:22 2022/08/05 22:24:32 7 wasm_exec.js:22 runtime.Callers wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.SDEBUG wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.freelock wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1 wasm_exec.js:22 syscall/js.handleEvent wasm_exec.js:22 runtime.handleEvent wasm_exec.js:22 runtime.goexit wasm_exec.js:22 2022/08/05 22:24:32 UNLOCkED ---------------------------------------------------------------------- *wasm_exec.js:22 2022/08/05 22:24:32 clickactive-filter-anchorwasm_exec.js:22 2022/08/05 22:24:32 LOCKING ====================================================================wasm_exec.js:22 2022/08/05 22:24:32 LOCkED -----------------------------------------------------------------*----- wasm_exec.js:22 2022/08/05 22:24:32 6 wasm_exec.js:22 runtime.Callers wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.SDEBUG wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1 wasm_exec.js:22 syscall/js.handleEvent wasm_exec.js:22 runtime.handleEvent wasm_exec.js:22 runtime.goexit *wasm_exec.js:22 2022/08/05 22:24:32 focusTodo-Appwasm_exec.js:22 2022/08/05 22:24:32 LOCKING* ==================================================================== wasm_exec.js:22 fatal error: all goroutines are asleep - deadlock! wasm_exec.js:22 wasm_exec.js:22 goroutine 1 [chan receive]: wasm_exec.js:22 github.com/atdiar/particleui.(*Router).ListenAndServe(0x103d940, {0x4d820, 0x8}, 0x4c6300, 0x61028) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/router.go:467 +0x3a wasm_exec.js:22 main.main() wasm_exec.js:22 /home/atd/Desktop/Projects/todomvc/main.go:228 +0x1db wasm_exec.js:22 wasm_exec.js:22 goroutine 7 [semacquire]: wasm_exec.js:22 sync.runtime_SemacquireMutex(0x2602c4, 0x0, 0x1) wasm_exec.js:22 /usr/local/go/src/runtime/sema.go:71 +0x2 wasm_exec.js:22 sync.(*Mutex).lockSlow(0x2602c0) wasm_exec.js:22 /usr/local/go/src/sync/mutex.go:162 +0x26 wasm_exec.js:22 sync.(*Mutex).Lock(0x2602c0) wasm_exec.js:22 /usr/local/go/src/sync/mutex.go:81 +0x7 wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1({{}, 0x7ff8000100000018, 0x11d3848}, {0x121b1e0, 0x1, 0x1}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/drivers/js/events.go:106 +0x21 wasm_exec.js:22 syscall/js.handleEvent() wasm_exec.js:22 /usr/local/go/src/syscall/js/func.go:94 +0x26 wasm_exec.js:22 syscall/js.Value.Call({{}, 0x7ff800010000003e, 0x410740}, {0x4ab3f, 0x5}, {0x0, 0x0, 0x0}) wasm_exec.js:22 /usr/local/go/src/syscall/js/js.go:379 +0x3 wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func10.7.2({0x8e540, 0x1206aa0}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/drivers/js/javascript.go:873 +0x57 wasm_exec.js:22 github.com/atdiar/particleui.(*MutationHandler).Handle(...) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:113 wasm_exec.js:22 github.com/atdiar/particleui.(*mutationHandlers).Handle(...) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:95 wasm_exec.js:22 github.com/atdiar/particleui.(*MutationCallbacks).DispatchEvent(0x40c148, {0x8e540, 0x1206aa0}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:62 +0x3c wasm_exec.js:22 github.com/atdiar/particleui.(*Element).Set(0x4c6240, {0x4ab21, 0x5}, {0x4ff87, 0xd}, {0x8e258, 0x121b1c0}, {0x0, 0x0, 0x0}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/uielement.go:1317 +0x7f wasm_exec.js:22 github.com/atdiar/particleui.(*Router).GoTo(0x103d940, {0x745dd0, 0x7}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/router.go:177 +0x4b wasm_exec.js:22 github.com/atdiar/particleui.(*Router).NewLink.func4({0x8e540, 0x1206960}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/router.go:859 +0xf wasm_exec.js:22 github.com/atdiar/particleui.(*MutationHandler).Handle(...) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:113 wasm_exec.js:22 github.com/atdiar/particleui.(*mutationHandlers).Handle(...) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:95 wasm_exec.js:22 github.com/atdiar/particleui.(*MutationCallbacks).DispatchEvent(0x40c708, {0x8e540, 0x1206960}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/mutation.go:62 +0x3c wasm_exec.js:22 github.com/atdiar/particleui.(*Element).Set(0x7852c0, {0x4ab21, 0x5}, {0x4d3e8, 0x8}, {0x8e198, 0x213128}, {0x0, 0x0, 0x0}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/uielement.go:1317 +0x7f wasm_exec.js:22 github.com/atdiar/particleui.Link.Activate({0x7852c0}, {0x1210be0, 0x1, 0x1}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/router.go:742 +0x7 wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.Anchor.FromLink.func3({0x8e6d0, 0x1206910}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/drivers/js/javascript.go:1842 +0xf wasm_exec.js:22 github.com/atdiar/particleui.EventHandler.Handle(...) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/event.go:198 wasm_exec.js:22 github.com/atdiar/particleui.EventListeners.Handle({0x563b90}, {0x8e6d0, 0x1206910}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/event.go:129 +0x69 wasm_exec.js:22 github.com/atdiar/particleui.(*Element).Handle(0x785740, {0x8e6d0, 0x1206910}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/uielement.go:449 +0x7 wasm_exec.js:22 github.com/atdiar/particleui.(*Element).DispatchEvent(0x785740, {0x8e6d0, 0x1206910}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/uielement.go:482 +0x11 wasm_exec.js:22 github.com/atdiar/particleui/drivers/js.glob..func2.1({{}, 0x7ff8000100000133, 0x11d2e10}, {0x11f1fb0, 0x1, 0x1}) wasm_exec.js:22 /home/atd/Desktop/Projects/particleui/drivers/js/events.go:177 +0xe3 wasm_exec.js:22 syscall/js.handleEvent() wasm_exec.js:22 /usr/local/go/src/syscall/js/func.go:94 +0x26 Any idea? -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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