Windows DirectoryWatcher buffer exhaustion recovery workaround. #2149
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| File | Coverage |
|---|---|
| pkgs/watcher/lib/src/directory_watcher.dart | 💚 57 % |
| pkgs/watcher/lib/src/directory_watcher/windows.dart | 💔 0 % ⬇️ NaN % |
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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
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| pkgs/bazel_worker/benchmark/benchmark.dart |
| pkgs/bazel_worker/example/client.dart |
| pkgs/bazel_worker/example/worker.dart |
| pkgs/benchmark_harness/integration_test/perf_benchmark_test.dart |
| pkgs/boolean_selector/example/example.dart |
| pkgs/clock/lib/clock.dart |
| pkgs/clock/lib/src/clock.dart |
| pkgs/clock/lib/src/default.dart |
| pkgs/clock/lib/src/stopwatch.dart |
| pkgs/clock/lib/src/utils.dart |
| pkgs/clock/test/clock_test.dart |
| pkgs/clock/test/default_test.dart |
| pkgs/clock/test/stopwatch_test.dart |
| pkgs/clock/test/utils.dart |
| pkgs/coverage/lib/src/coverage_options.dart |
| pkgs/html/example/main.dart |
| pkgs/html/lib/dom.dart |
| pkgs/html/lib/dom_parsing.dart |
| pkgs/html/lib/html_escape.dart |
| pkgs/html/lib/parser.dart |
| pkgs/html/lib/src/constants.dart |
| pkgs/html/lib/src/encoding_parser.dart |
| pkgs/html/lib/src/html_input_stream.dart |
| pkgs/html/lib/src/list_proxy.dart |
| pkgs/html/lib/src/query_selector.dart |
| pkgs/html/lib/src/token.dart |
| pkgs/html/lib/src/tokenizer.dart |
| pkgs/html/lib/src/treebuilder.dart |
| pkgs/html/lib/src/utils.dart |
| pkgs/html/test/dom_test.dart |
| pkgs/html/test/parser_feature_test.dart |
| pkgs/html/test/parser_test.dart |
| pkgs/html/test/query_selector_test.dart |
| pkgs/html/test/selectors/level1_baseline_test.dart |
| pkgs/html/test/selectors/level1_lib.dart |
| pkgs/html/test/selectors/selectors.dart |
| pkgs/html/test/support.dart |
| pkgs/html/test/tokenizer_test.dart |
| pkgs/html/test/trie_test.dart |
| pkgs/html/tool/generate_trie.dart |
| pkgs/pubspec_parse/test/git_uri_test.dart |
| pkgs/stack_trace/example/example.dart |
| pkgs/watcher/test/custom_watcher_factory_test.dart |
| pkgs/yaml_edit/example/example.dart |
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Add workaround.
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Package publishing
Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation. |
| error.message.startsWith('Directory watcher closed unexpectedly')) { | ||
| unawaited(_watchSubscription?.cancel()); | ||
| _eventsController.addError(error, stackTrace); | ||
| // Wait to work around https://github.com/dart-lang/sdk/issues/61378. |
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Not sure what's going on with the reformatting ... this is the only actual change.
| unawaited(_watchSubscription?.cancel()); | ||
| _eventsController.addError(error, stackTrace); | ||
| // Wait to work around https://github.com/dart-lang/sdk/issues/61378. | ||
| await Future<void>.delayed(Duration.zero); |
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It would be helpful if the comment explained the theory for why waiting for zero time helps here. Is the theory here that by letting the event loop run, we (hopefully) drain the queue of pending events from the OS, so it's more likely to be willing to start watching again?
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I discovered that the workaround only improves things, it's still not 100%, so I'll hold off a bit to see if we can learn more :) ... and then update / document.
I think it's actually nothing to do with the OS, it's the OS-interfacing code in the Dart VM that gets into a bad state sometimes. So the delay is something to do with that.
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Tweaked the workaround to wait 1ms; this seems to work 100% of the time. I wouldn't bet on it, but I think it's a good enough workaround until the SDK fix arrives.
Added a short explanation and direction to see the issue for more information.
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Updated the workaround, changed the version to I think this is ready now, please take another look @sigurdm :) |
This is a fun issue dart-lang/build#4154 which looks like an SDK bug dart-lang/sdk#61378 but fortunately I found what seems to be a simple workaround.
The test that's added reliably fails without the fix; it doesn't always fail on the same retry, but 200 retries seems to be plenty. Fortunately it's fast.
And then, with the workaround, it passes :)
It seems reasonably likely that there can be an SDK fix, but the workaround seems useful+safe enough to publish, what do you think please?