Shortened stack trace from VM #44169
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ghost
self-assigned this
mkustermann
added
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area-vm
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I've tried reproducing this, but patching 168485 onto 95e4e03 has given me no exceptions in the hour or so I've let it run now. (It appears to be an infinite loop?) @jensjoha, do you have a reproducing example I can try, or has something changed in the meantime? As for the issue described, it is suspicious that you're seeing two gaps at the end of the trace, though I don't currently have a good guess how that could happen. |
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And yes, it's an infinite loop, but it crashes up front (when it crashes). The above is verified (on my machine at least): |
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Gotcha. I'll give that a try. Thanks, Jens! |
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I've narrowed it down to: Which I've boiled down to this: void clear() => 'Does nothing';
myAction() async {
await 0;
throw 'async throw from myAction.';
}
// `myaction` is run immediately in Future.sync, eventually throws, which is then
// being passed on to the internals of whenComplete, which runs `clear` and
// rethrows from there.
doThings() async => Future.sync(() => myAction()).whenComplete(clear);
main() async => await doThings();So when we try do the stack unwinding we have:
And from there we run out of chain to lazily unwind, hence the short stack with --lazy-async-stack. @mkustermann, do you see anything we can do about this? |
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@jensjoha The code in the frontend uses diff --git a/pkg/front_end/lib/src/fasta/compiler_context.dart b/pkg/front_end/lib/src/fasta/compiler_context.dart
index e64cd29900e..fffd1ac7817 100644
--- a/pkg/front_end/lib/src/fasta/compiler_context.dart
+++ b/pkg/front_end/lib/src/fasta/compiler_context.dart
@@ -120,9 +120,13 @@ class CompilerContext {
/// Perform [action] in a [Zone] where [this] will be available as
/// `CompilerContext.current`.
Future<T> runInContext<T>(Future<T> action(CompilerContext c)) {
- return runZoned(
- () => new Future<T>.sync(() => action(this)).whenComplete(clear),
- zoneValues: {compilerContextKey: this});
+ return runZoned(() async {
+ try {
+ await action(this);
+ } finally {
+ clear();
+ }
+ }, zoneValues: {compilerContextKey: this});
}in the frontend package? @cskau-g One action item we should definitely take here is that we should avoid emitting consecutive We could consider writing Alternatively we could make VM use |
TEST=tools/test.py -n dartk-linux-release-x64 vm/dart_2/causal_stacks Bug: #44169 Change-Id: I27dbe298ea30ef562984788223080fcb65f43da4 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172961 Reviewed-by: Tess Strickland <[email protected]> Commit-Queue: Clement Skau <[email protected]>
Done: https://dart-review.googlesource.com/c/sdk/+/172961
I will follow up on this. |
TEST=tools/test.py -n dartk-linux-release-x64 vm/dart_2/causal_stacks Bug: #44169 Change-Id: Ia5810ca3585f8e90b6fb91827a892a038e82f13b Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/173264 Commit-Queue: Clement Skau <[email protected]> Reviewed-by: Martin Kustermann <[email protected]>
Done: https://dart-review.googlesource.com/c/sdk/+/173264 That should address all the VM concerns for this issue. I'll reassign to you, @jensjoha, to decide if you folks want to follow up on Martin's suggestion in #44169 (comment). |
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Reintroducing the crash I now get which seems fine =) |
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With CL https://dart-review.googlesource.com/c/sdk/+/168485/9 (on top of what it's on top of, i.e. 42ac762) it crashes when loading the dill file (obviously it shouldn't, I'll look into that separately) if you run for instance
out/ReleaseX64/dart pkg/front_end/test/constant_evaluator_benchmark.dart --platform=out/ReleaseX64/dart-sdk/lib/_internal/dart2js_platform.dill pkg/compiler/bin/dart2js.dart --target=dart2js --nnbdlike this:which is missing something at the end... e.g. which line in
constant_evaluator_benchmark.dartactually came to this path?If I add
--no-lazy-async-stacks --causal-async-stacksI instead getwhich gives me my answer, so I assume the shortened stacktrace is a bug with the lazy async stuff.
/cc @cskau-g
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