I had an issue reported against the Dart extension at Dart-Code/Dart-Code#5690 that the built-in terminal was very slow during test runs. It seemed to be related to a large amount of logging output from the test.
In an attempt to reproduce this, I created a simple test that just sends a lot of output events:
import 'package:test/test.dart';
void main() {
test('calculate', () async {
for (var i = 0; i < 10000; i++) {
print('Iteration $i');
await Future.delayed(const Duration(microseconds: 750));
}
});
}When I run this, VS Code completely hangs for long periods during the run and takes a long time to "catch up" with the output.
Profiling the extension host didn't reveal anything, but profiling the VS Code UI does show a lot of scripting. I'm not familiar with this code, but I think the call tree suggests that the output events are triggering decoration updates and perhaps that's quite expensive:
Perhaps any updates triggered by output should be batched/debounced, since a lot of output is not uncommon when logging/debugging things.
Here is the exported CPU profile: vs_code_slow_test_profile.zip
I had an issue reported against the Dart extension at Dart-Code/Dart-Code#5690 that the built-in terminal was very slow during test runs. It seemed to be related to a large amount of logging output from the test.
In an attempt to reproduce this, I created a simple test that just sends a lot of output events:
When I run this, VS Code completely hangs for long periods during the run and takes a long time to "catch up" with the output.
Profiling the extension host didn't reveal anything, but profiling the VS Code UI does show a lot of scripting. I'm not familiar with this code, but I think the call tree suggests that the output events are triggering decoration updates and perhaps that's quite expensive:
Perhaps any updates triggered by output should be batched/debounced, since a lot of output is not uncommon when logging/debugging things.
Here is the exported CPU profile: vs_code_slow_test_profile.zip