Dart DevTools: Loading CPU profile in JIT doesn't work

[jensjoha]

Say I run

out/ReleaseX64/dart-sdk/bin/dart --enable-vm-service --pause_isolates_on_exit --profiler pkg/_fe_analyzer_shared/test/scanner_benchmark.dart pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart --bytes

and launch devtools. I go to the "CPU Profiler" tab, click "Load all CPU samples". Then it just sits there, "Fetching CPU samples" forever.
In the javascript console I can see this stuff:

completePageInitializationIfReady_  {message: 'The message port closed before a response was received.'}

Attempting to load DevTools with canvaskit renderer.

Version: 2.43.0, Renderer: canvaskit

WebSocket connection to 'ws://127.0.0.1:46349/uqClOtdj8j8=' failed: 

[Dart Tooling Daemon connection failed.]: WebSocketChannelException: Instance of 'minified:OT'

DevTools log level changed to INFO

Could not find release notes for DevTools version 2.43.0.

Attempted to call extension 'ext.flutter.inspector.structuredErrors', but no service with that name exists

Could not time async operation "cpuProfileProcessingTime" because an exception was thrown:
Null check operator used on a null value
TypeError: Cannot read properties of undefined (reading 'd')
    at bNN.$2$current$parent (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:89924:44)
    at bNN.$2$current$parent (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:89928:83)
    at Object.cAi (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:14693:32)
    at http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:14601:129
    at bOY.a (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:5131:63)
    at bOY.$2 (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:62218:14)
    at Object.k (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:5117:10)
    at Object.To (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:14631:10)
    at http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:50796:14
    at bOY.a (http://127.0.0.1:8181/EY_ENZZmO58=/devtools/main.dart.js:5131:63)

Uncaught Error: Null check operator used on a null value
    at bNN.$2$current$parent (cpu_profile_model.dart:1261:39)
    at bNN.$2$current$parent (cpu_profile_model.dart:1372:9)
    at Object.cAi (cpu_profile_model.dart:1380:5)
    at cpu_profile_model.dart:562:50
    at bOY.a (async_patch.dart:311:19)
    at bOY.$2 (async_patch.dart:336:23)
    at Object.k (async_patch.dart:241:3)
    at Object.To (cpu_profile_model.dart:556:11)
    at cpu_profile_service.dart:64:42
    at bOY.a (async_patch.dart:311:19)

[zoneGuarded]: Null check operator used on a null value
../../../lib/src/screens/profiler/cpu_profile_model.dart 1261:39                   _extension#0|generateStackFramesJson.processStackFrame
../../../lib/src/screens/profiler/cpu_profile_model.dart 1372:9                    _extension#0|generateStackFramesJson.processStackFrame
../../../lib/src/screens/profiler/cpu_profile_model.dart 1380:5                    CpuSamples.<anonymous extension>.generateStackFramesJson
../../../lib/src/screens/profiler/cpu_profile_model.dart 562:50                    CpuProfileData.generateFromCpuSamples
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 311:19  _wrapJsFunctionForAsync
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 336:23  _wrapJsFunctionForAsync.<anonymous function>
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 241:3   _asyncStartSync
../../../lib/src/screens/profiler/cpu_profile_model.dart 556:11                    CpuProfileData.generateFromCpuSamples
../../../lib/src/screens/profiler/cpu_profile_service.dart 64:42                   CpuProfilerExtension.getCpuProfile
org-dartlang-sdk:///dart-sdk/lib/_internal/js_runtime/lib/async_patch.dart 311:19  _wrapJsFunctionForAsync

I am running through a ssh tunnel with port 8181 open btw.

Worth noting though is that if I instead do

pkg/vm/tool/precompiler2 pkg/_fe_analyzer_shared/test/scanner_benchmark.dart test.aot
out/ReleaseX64/dartaotruntime --enable-vm-service --pause_isolates_on_exit --profiler test.aot pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart --bytes

it works. It loads the profile and there are no errors in the console.

[dart-github-bot]

Summary: Loading CPU profiles in Dart DevTools fails with JIT compilation, showing WebSocket connection and null pointer errors. AOT compilation works correctly.

[a-siva]

//cc @derekxu16

[bkonyi]

This is likely a DevTools issue and should be filed over in flutter/devtools.

[derekxu16]

Closing in favour of flutter/devtools#8866.