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e151a81108
Original CL in patchset 1. Split-off https://dart-review.googlesource.com/c/sdk/+/238341 And pulled in fix https://dart-review.googlesource.com/c/sdk/+/238582 (Should merge cleanly when this lands later.) This CL implements the `Finalizer` in the GC. The GC is specially aware of two types of objects for the purposes of running finalizers. 1) `FinalizerEntry` 2) `Finalizer` (`FinalizerBase`, `_FinalizerImpl`) A `FinalizerEntry` contains the `value`, the optional `detach` key, and the `token`, and a reference to the `finalizer`. An entry only holds on weakly to the value, detach key, and finalizer. (Similar to how `WeakReference` only holds on weakly to target). A `Finalizer` contains all entries, a list of entries of which the value is collected, and a reference to the isolate. When a the value of an entry is GCed, the enry is added over to the collected list. If any entry is moved to the collected list, a message is sent that invokes the finalizer to call the callback on all entries in that list. When a finalizer is detached by the user, the entry token is set to the entry itself and is removed from the all entries set. This ensures that if the entry was already moved to the collected list, the finalizer is not executed. To speed up detaching, we use a weak map from detach keys to list of entries. This ensures entries can be GCed. Both the scavenger and marker tasks process finalizer entries in parallel. Parallel tasks use an atomic exchange on the head of the collected entries list, ensuring no entries get lost. The mutator thread is guaranteed to be stopped when processing entries. This ensures that we do not need barriers for moving entries into the finalizers collected list. Dart reads and replaces the collected entries list also with an atomic exchange, ensuring the GC doesn't run in between a load/store. When a finalizer gets posted a message to process finalized objects, it is being kept alive by the message. An alternative design would be to pre-allocate a `WeakReference` in the finalizer pointing to the finalizer, and send that itself. This would be at the cost of an extra object. Send and exit is not supported in this CL, support will be added in a follow up CL. Trying to send will throw. Bug: https://github.com/dart-lang/sdk/issues/47777 TEST=runtime/tests/vm/dart/finalizer/* TEST=runtime/tests/vm/dart_2/isolates/fast_object_copy_test.dart TEST=runtime/vm/object_test.cc Change-Id: Ibdfeadc16d5d69ade50aae5b9f794284c4c4dbab Cq-Include-Trybots: luci.dart.try:vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try,vm-ffi-android-debug-arm64c-try,dart-sdk-mac-arm64-try,vm-kernel-mac-release-arm64-try,pkg-mac-release-arm64-try,vm-kernel-precomp-nnbd-mac-release-arm64-try,vm-kernel-win-debug-x64c-try,vm-kernel-win-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-nnbd-win-release-ia32-try,vm-ffi-android-debug-arm-try,vm-precomp-ffi-qemu-linux-release-arm-try,vm-kernel-mac-debug-x64-try,vm-kernel-nnbd-mac-debug-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,benchmark-linux-try,flutter-analyze-try,flutter-frontend-try,pkg-linux-debug-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-optcounter-threshold-linux-release-x64-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238086 Reviewed-by: Martin Kustermann <kustermann@google.com> Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com> |
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| compiler | ||
| images | ||
| infra | ||
| aot_binary_size_analysis.md | ||
| dwarf_stack_traces.md | ||
| gc.md | ||
| index.md | ||
| pragmas.md | ||
| snapshot_profiling.md | ||
| types.md | ||