Triggering a hot-restart causes a web app to freeze

[elliette]

Steps to repro:

1. Run a Flutter web app
2. Open DevTools debugger
3. Trigger a hot-restart

Expected behavior:
web app restarts

Actual behavior:
web app freezes, hitting resume button does not unfreeze web app

I've managed to reproduce this on a couple web apps. I'm on Flutter main. I need to do more investigation to figure out when this started, and if it's related to changes in DevTools or package:dwds, etc.

FYI @bkonyi

[bkonyi]

Do you have a sample application that you can reproduce this consistently with?

[elliette]

Do you have a sample application that you can reproduce this consistently with?

I was able to repro with: https://github.com/elliette/flutter_hiking_app

[bkonyi]

I'm seeing the following messages in the DevTools console when triggering a hot restart from the debugger:

core_patch.dart:278 Uncaught Error: getObject: (-32603) Unexpected DWDS error for getObject: WipError -32000 Invalid remote object id
    at Object.Aq (core_patch.dart:787:58)
    at brL.$0 (vm_service.dart:265:34)
    at n8.cv (vm_service.dart:1933:8)
    at n8.Af (vm_service.dart:1119:7)
    at n8.Af (vm_service_wrapper.dart:167:18)
    at n8.ie (vm_service_wrapper.dart:152:15)
    at bIi.Aj (script_manager.dart:125:41)
    at script_manager.dart:77:12
    at bQn.a (async_patch.dart:310:19)
    at bQn.$2 (async_patch.dart:335:23)
coC @ core_patch.dart:278
aVI @ errors.dart:120
$0 @ zone.dart:1512
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1474
hG @ schedule_microtask.dart:148
MY @ stream_impl.dart:645
rZ @ stream_impl.dart:368
qB @ stream_controller.dart:812
m1 @ stream_controller.dart:663
C @ stream_controller.dart:618
$1 @ browser_web_socket.dart:83
$1 @ streams.dart:165
bQ4 @ zone.dart:1546
(anonymous) @ zone.dart:1531
u9 @ zone.dart:1428
ua @ zone.dart:1329
$1 @ zone.dart:1367
cB5 @ js_allow_interop_patch.dart:347
(anonymous) @ js_allow_interop_patch.dart:127Understand this error
core_patch.dart:278 Uncaught Error: getObject: (-32603) Unexpected DWDS error for getObject: WipError -32000 Invalid remote object id
    at Object.Aq (core_patch.dart:787:58)
    at brL.$0 (vm_service.dart:265:34)
    at n8.cv (vm_service.dart:1933:8)
    at n8.Af (vm_service.dart:1119:7)
    at n8.Af (vm_service_wrapper.dart:167:18)
    at n8.ie (vm_service_wrapper.dart:152:15)
    at bIi.Aj (script_manager.dart:125:41)
    at script_manager.dart:77:12
    at bQn.a (async_patch.dart:310:19)
    at bQn.$2 (async_patch.dart:335:23)
coC @ core_patch.dart:278
aVI @ errors.dart:120
$0 @ zone.dart:1512
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55Understand this error
js_util_patch.dart:81 [zoneGuarded]: getObject: (-32603) Unexpected DWDS error for getObject: WipError -32000 Invalid remote object id
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/core_patch.dart 787:58                  StackTrace.current
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 265:34  _OutstandingRequest
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 1933:8  VmService._call
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 1119:7  VmService.getObject
../../../lib/src/service/vm_service_wrapper.dart 167:18                                           VmServiceWrapper.getObject
../../../lib/src/service/vm_service_wrapper.dart 152:15                                           VmServiceWrapper.getObject[function-entry$2]
../../../lib/src/shared/managers/script_manager.dart 125:41                                       _ScriptCache.getScript
../../../lib/src/shared/managers/script_manager.dart 77:12                                        CodeViewController.getScriptForRef
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 310:19                 _wrapJsFunctionForAsync
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 335:23                 _wrapJsFunctionForAsync.<anonymous function>

cHv @ js_util_patch.dart:81
$1 @ logger_helpers.dart:34
bQ4 @ zone.dart:1546
(anonymous) @ zone.dart:1531
u9 @ zone.dart:1428
ua @ zone.dart:1329
qB @ stream_impl.dart:381
m1 @ stream_impl.dart:312
qB @ broadcast_stream_controller.dart:389
C @ broadcast_stream_controller.dart:257
ajR @ logger.dart:314
aY @ logger.dart:238
(anonymous) @ logger.dart:296
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ app_error_handling.dart:149
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ app_error_handling.dart:156
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ app_error_handling.dart:120
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ app_error_handling.dart:136
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ http.dart:164
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
bV @ async_patch.dart:205
j @ async_patch.dart:263
(anonymous) @ response.dart:64
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
$0 @ future_impl.dart:807
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1869
aK6 @ future_impl.dart:806
m3 @ future_impl.dart:766
bV @ future_impl.dart:101
$1 @ js_util_patch.dart:565
Promise.then
ir @ js_util_patch.dart:578
(anonymous) @ js_interop_patch.dart:161
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$0 @ async_patch.dart:417
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1869
aK6 @ future_impl.dart:806
m3 @ future_impl.dart:766
bV @ future_impl.dart:101
$1 @ js_util_patch.dart:565
Promise.then
ir @ js_util_patch.dart:578
(anonymous) @ js_interop_patch.dart:161
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$0 @ async_patch.dart:417
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1869
aK6 @ future_impl.dart:806
m3 @ future_impl.dart:766
bV @ future_impl.dart:101
$1 @ js_util_patch.dart:565
Promise.then
ir @ js_util_patch.dart:578
(anonymous) @ js_interop_patch.dart:161
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$0 @ async_patch.dart:417
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1869
aK6 @ future_impl.dart:806
m3 @ future_impl.dart:766
bV @ future_impl.dart:101
$1 @ js_util_patch.dart:565
Promise.then
ir @ js_util_patch.dart:578
(anonymous) @ js_interop_patch.dart:161
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$0 @ async_patch.dart:490
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55
childList
$1 @ async_patch.dart:68
cbD @ async_patch.dart:33
bQ5 @ zone.dart:1623
wP @ zone.dart:1869
aK6 @ future_impl.dart:806
m3 @ future_impl.dart:766
bV @ future_impl.dart:101
$1 @ js_util_patch.dart:565
Promise.then
ir @ js_util_patch.dart:578
(anonymous) @ js_interop_patch.dart:161
(anonymous) @ async_patch.dart:310
$2 @ async_patch.dart:335
$1 @ async_patch.dart:286
u9 @ zone.dart:1849
$0 @ future_impl.dart:189
Hy @ future_impl.dart:980
uL @ future_impl.dart:723
$0 @ future_impl.dart:807
cCR @ schedule_microtask.dart:40
cDm @ schedule_microtask.dart:49
$1 @ async_patch.dart:55Understand this error
js_util_patch.dart:81 [zoneGuarded]: getObject: (-32603) Unexpected DWDS error for getObject: WipError -32000 Invalid remote object id
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/core_patch.dart 787:58                  StackTrace.current
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 265:34  _OutstandingRequest
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 1933:8  VmService._call
../../../../../../rc/tmpnkc_tcbj/hosted/pub.dev/vm_service-15.0.0/lib/src/vm_service.dart 1119:7  VmService.getObject
../../../lib/src/service/vm_service_wrapper.dart 167:18                                           VmServiceWrapper.getObject
../../../lib/src/service/vm_service_wrapper.dart 152:15                                           VmServiceWrapper.getObject[function-entry$2]
../../../lib/src/shared/managers/script_manager.dart 125:41                                       _ScriptCache.getScript
../../../lib/src/shared/managers/script_manager.dart 77:12                                        CodeViewController.getScriptForRef
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 310:19                 _wrapJsFunctionForAsync
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 335:23                 _wrapJsFunctionForAsync.<anonymous function>

This doesn't seem to be an issue if we execute a hot restart from the CLI, so I'm guessing these calls to getObject are somehow getting DWDS into a bad state.

[elliette]

I think I've tracked down the error.

Here is the Flutter commit where this starts happening: flutter/flutter@edbdafd

Which includes these commits to DevTools:
e4d5a4c...f10e8df

I'm guessing this is the culprit: #8991

Will send out a fix 🤞

[elliette]

DWDS is sending a resume event after a hot-restart (I believe here): https://github.com/dart-lang/webdev/blob/c8b1cfa9d12c680b612eb1ed7a6b9f99fcce3ac3/dwds/lib/src/services/chrome_proxy_service.dart#L309-L314

I confirmed that checking for a resume event here fixes this:

devtools/packages/devtools_app/lib/src/screens/debugger/breakpoint_manager.dart

Lines 93 to 100 in 5a5c19c

	if ([
	EventKind.kPauseStart,
	EventKind.kPausePostRequest,
	].contains(pauseEventKind)) {
	await serviceConnection.serviceManager.isolateManager.resumeIsolate(
	isolateRef,
	);
	}

I need to do more investigation that this doesn't cause any other issues though. @bkonyi I'm not sure if the better fix is for package:dwds to not send the resume event.