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Large lists in locals/watch windows can hang #4204
Description
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).
Activity
DanTup commentedon Oct 11, 2022
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.
[dds/dap] Improve handling of lists in variables requests
DanTup commentedon Oct 18, 2022
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": truein VS Code settings).