Implement WeakReference, Finalizer and NativeFinalizer in VM
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Use area-vm for VM related issues, including code coverage, and the AOT and JIT backends.
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This does not yet add `Finalizable` to `dart:ffi`, but already extends the ffi_verifier to not give errors on implementing it. Bug: #47777 Change-Id: I381d4954f39ae031d540cdbe97b112edafc25df8 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/227721 Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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A simple implementation which use two objects per weak reference and two loads for a load from a weak reference. This can be optimized later. TEST=runtime/tests/vm/dart/finalizer/weak_reference_run_gc_test.dart Design doc: go/dart-vm-weakreference Bug: #47777 Optimization tracking bug: #48162 Change-Id: Id0b71caef940c610f85212fda4bdc267bf84edea Cq-Include-Trybots: luci.dart.try:analyzer-linux-release-try,analyzer-nnbd-linux-release-try,app-kernel-linux-debug-x64-try,benchmark-linux-try,dart-sdk-linux-try,front-end-linux-release-x64-try,front-end-nnbd-linux-release-x64-try,pkg-linux-debug-try,vm-canary-linux-debug-try,vm-ffi-android-debug-arm-try,vm-ffi-android-debug-arm64c-try,vm-fuchsia-release-x64-try,vm-kernel-checked-linux-release-x64-try,vm-kernel-gcc-linux-try,vm-kernel-linux-debug-x64c-try,vm-kernel-mac-debug-x64-try,vm-kernel-asan-linux-release-x64-try,vm-kernel-msan-linux-release-x64-try,vm-kernel-nnbd-linux-debug-ia32-try,vm-kernel-nnbd-win-debug-x64-try,vm-kernel-nnbd-win-release-ia32-try,vm-kernel-nnbd-linux-debug-x64-try,vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-android-release-arm_x64-try,vm-kernel-precomp-android-release-arm64c-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-win-debug-x64c-try,vm-kernel-reload-linux-debug-x64-try,vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-win-debug-ia32-try,vm-kernel-win-debug-x64-try,vm-precomp-ffi-qemu-linux-release-arm-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/228206 Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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Feb 5, 2022
This CL implements `Finalizable` by means of a CFE transform. The transform is implemented in the existing FFI transform to avoid the overhead of traversing the AST an extra time. The FFI transform slows down ~15-30% on Flutter Gallery. For more info see the design doc. TEST=`dart pkg/vm/test/transformations/ffi_test.dart` Design doc: go/dart-vm-finalizable Bug: #47777 Change-Id: I0bf9dead90a61631b7f215dc19fbaa9e40e63c8d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/227501 Reviewed-by: Slava Egorov <vegorov@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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Mar 4, 2022
In a follow up CL, we lookup members in `dart:ffi` lazily. Also removes ffi member from store that was never used. Split off https://dart-review.googlesource.com/c/sdk/+/229544 to make that CL smaller. TEST=SDK build Bug: #47777 Change-Id: I2eed23b57ff92217bfae8fabfc84cf75cb62f313 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/234942 Reviewed-by: Aske Simon Christensen <askesc@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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Mar 11, 2022
This CL documents the existence of `RawStoreFieldInstr` and why a `RawLoadFieldInstr` is not needed. Also it adds a unit test exercising `RawStoreFieldInstr`. With this type of unit test we can land IL instructions without using them flow graph builder yet. Split off https://dart-review.googlesource.com/c/sdk/+/229544. TEST=runtime/vm/compiler/backend/il_test.cc vm/cc/IRTest_RawStoreField Bug: #47777 Change-Id: I20115fd2f72abe705447aa4b16ca6ecb30ad05fa Cq-Include-Trybots: luci.dart.try:vm-kernel-win-debug-x64-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/234980 Reviewed-by: Tess Strickland <sstrickl@google.com>
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Introduces a new IL instruction to load the THR register as an untagged value in IL. Split off from https://dart-review.googlesource.com/c/sdk/+/229544. TEST=runtime/vm/compiler/backend/il_test.cc vm/cc/IRTest_LoadThread Bug: #47777 Change-Id: Ic6bf59b05c89593773dbc91d623cd0078657c8ab Cq-Include-Trybots: luci.dart.try:vm-kernel-win-debug-x64-try,vm-kernel-linux-debug-ia32-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/235602 Reviewed-by: Slava Egorov <vegorov@google.com> Reviewed-by: Martin Kustermann <kustermann@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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Mar 22, 2022
This CL implements the `Finalizer` in the GC. (This CL does not yet implement `NativeFinalizer`.) 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: #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: I03e6b4a46212316254bf46ba3f2df333abaa686c 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/+/229544 Reviewed-by: Lasse Nielsen <lrn@google.com> Reviewed-by: Slava Egorov <vegorov@google.com> 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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Mar 22, 2022
This reverts commit 7dca34c. Reason for revert: b/226085355 dart_vm_test crashing. Unclear what the cause is. Reverting so we can triage the issue. TEST=This is a revert. Original change's description: > [vm] Implement `Finalizer` > > This CL implements the `Finalizer` in the GC. > > (This CL does not yet implement `NativeFinalizer`.) > > 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: #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: I03e6b4a46212316254bf46ba3f2df333abaa686c > 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/+/229544 > Reviewed-by: Lasse Nielsen <lrn@google.com> > Reviewed-by: Slava Egorov <vegorov@google.com> > Reviewed-by: Martin Kustermann <kustermann@google.com> > Reviewed-by: Ryan Macnak <rmacnak@google.com> > Commit-Queue: Daco Harkes <dacoharkes@google.com> TBR=lrn@google.com,vegorov@google.com,kustermann@google.com,rmacnak@google.com,dacoharkes@google.com Change-Id: I991f6e49896d18a8d70210cf315d858b462d66c9 No-Presubmit: true No-Tree-Checks: true No-Try: true Bug: #47777 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/+/238080 Reviewed-by: Slava Egorov <vegorov@google.com> Reviewed-by: Daco Harkes <dacoharkes@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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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: #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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This CL implements `NativeFinalizer` in the GC. `FinalizerEntry`s are extended to track `external_size` and in which `Heap::Space` the finalizable value is. On attaching a native finalizer, the external size is added to the relevant heap. When the finalizable value is promoted from new to old space, the external size is promoted as well. And when a native finalizer is run or is detached, the external size is removed from the relevant heap again. In contrast to Dart `Finalizer`s, `NativeFinalizer`s are run on isolate shutdown. When the `NativeFinalizer`s themselves are collected, the finalizers are not run. Users should stick the native finalizer in a global variable to ensure finalization. We will revisit this design when we add send and exit support, because there is a design space to explore what to do in that case. This current solution promises the least to users. In this implementation native finalizers have a Dart entry to clean up the entries from the `all_entries` field of the finalizer. We should consider using another data structure that avoids the need for this Dart entry. See the TODO left in the code. Bug: #47777 TEST=runtime/tests/vm/dart(_2)/isolates/fast_object_copy_test.dart TEST=runtime/vm/object_test.cc TEST=tests/ffi(_2)/vmspecific_native_finalizer_* Change-Id: I8f594c80c3c344ad83e1f2de10de028eb8456121 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-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/+/236320 Reviewed-by: Martin Kustermann <kustermann@google.com> Reviewed-by: Slava Egorov <vegorov@google.com> Commit-Queue: Daco Harkes <dacoharkes@google.com>
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Now that Finalizer and NativeFinalizer has landed, can this issue be closed? |
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For reference: language proposal.
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