Large lists in locals/watch windows can hang

[DanTup]

Reported on StackOverflow: https://stackoverflow.com/q/73921614/25124

import 'dart:typed_data';

void main() {
  Uint8List inputBytes = Uint8List.fromList(List.filled(100000000, 0));
  print(''); // Breakpoint here
}

We send a getObject() request but there's no offset/length s presumably it's trying to send the entire list back which is huge. It's possible being a Uint8List complicates things, but a normal List (List.filled(100000000, 0)) has issues too.

<== {
	"jsonrpc": "2.0",
	"method": "streamNotify",
	"params": {
		"streamId": "Debug",
		"event": {
			"type": "Event",
			"kind": "PauseBreakpoint",
			// ...
			"topFrame": {
				// ...
				"vars": [
					{
						"type": "BoundVariable",
						"name": "inputBytes",
						"value": {
							"type": "@Instance",
							// ...
							"identityHashCode": 0,
							"kind": "List", // We know it's a list
							"id": "objects/1",
							"length": 100000000 // And its length
						},
						"declarationTokenPos": 20,
						"scopeStartTokenPos": 39,
						"scopeEndTokenPos": 142
					}
				],
				"index": 0
			}
		}
	}
}

==> {
	"jsonrpc": "2.0",
	"id": "40",
	"method": "getObject",
	"params": {
		"isolateId": "isolates/2007599444226843",
		"objectId": "objects/1"
	}
}

For Uint8List the kind is Uint8List but it still has a length, and the kinds that provide lists are documented in https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#instance (string, map, and various lists).

[DanTup]

Fixed with https://dart-review.googlesource.com/c/sdk/+/263620 in the new DAPs.

Since this change is in the SDK, it'll show up in an SDK update.

[DanTup]

Fixed by dart-lang/sdk@ae352fe. This will ship in an upcoming SDK release and applies to the new debug adapters (which will roll out progressively, but can be opted-in with "dart.previewSdkDaps": true in VS Code settings).