[Impeller] libImpeller: Dispose thread local caches on each Vulkan frame#182402
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The Impeller Vulkan back end caches command pools in thread-local storage. These caches can grow unbounded unless the embedder calls ContextVK::DisposeThreadLocalCachedResources() This PR ensures that libImpeller Vulkan apps do this on each frame by calling DisposeThreadLocalCachedResources inside the ImpellerVulkanSwapchainAcquireNextSurfaceNew API.
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This pull request modifies the SwapchainVK::AcquireNextSurface method to call DisposeThreadLocalCachedResources on the Vulkan context. This is done at the beginning of each frame, before acquiring a new surface from the swapchain. The change, located in the Impeller interop layer for Vulkan, aims to prevent unbounded growth of thread-local caches, such as command pools and descriptor pools, for applications using libImpeller.
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Were these caches created as a means to improve performance? What sort of performance ramifications will dumping these each frame have? Is the growth bounded by the largest usage of a frame, as opposed to being additive? If so maybe a better heuristic would be to dispose of the caches if the cache size is much greater than the actual usage.
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The use of thread-local storage in the Vulkan back end was based on recommendations for improving the performance of command pools (see #133198). Per-thread command pools are reused within the scope of a single frame. This PR matches the behavior of the engine's use of Impeller. In the engine, the cleanup of the thread-local storage is done for each frame within |
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@jason-simmons you are talking about this: That is happening at the end of a frame where this is happening at the beginning of a frame. Disposing of the caches requires acquiring a mutex so it seems like doing so after encoding a frame would have better performance. |
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In the The performance cost is generally insignificant. |
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In the SurfaceContextVK used by the engine, MarkFrameEnd/ContextVK::DisposeThreadLocalCachedResources is called inside AcquireNextSurface.
The performance cost is generally insignificant.
Sounds good, this does look like what we are doing in the engine proper. Even at 120hz a lock probably isn't a big deal even when contested but if we can easily place it somewhere where we aren't holding onto a system resource it seems like an easy problem to avoid.
We have an integration that already covers this code, right? I'm not too familiar with this setup.
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@jason-simmons friendly ping, this was approved before the holiday weekend. But I did have one question about test coverage. |
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The libImpeller library has some tests that are built into the However, the playground test framework is using the main Impeller Vulkan |
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flutter/flutter@91b2d41...dad6f9d 2026-02-23 engine-flutter-autoroll@skia.org Roll Packages from 9da22bf to 12b43a1 (19 revisions) (flutter/flutter#182758) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 55fae1660572 to 9a5a3c92c336 (7 revisions) (flutter/flutter#182749) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 256e2b47b303 to 55fae1660572 (1 revision) (flutter/flutter#182741) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 141ed451f007 to 256e2b47b303 (1 revision) (flutter/flutter#182732) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from e59de8a12e7e to 141ed451f007 (1 revision) (flutter/flutter#182729) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from f6ea7ef42d14 to e59de8a12e7e (1 revision) (flutter/flutter#182726) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 34fa7b2373f3 to f6ea7ef42d14 (1 revision) (flutter/flutter#182721) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from 3ca547c8b816 to 34fa7b2373f3 (2 revisions) (flutter/flutter#182711) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from c91ad88e89f8 to 3ca547c8b816 (9 revisions) (flutter/flutter#182696) 2026-02-21 victorsanniay@gmail.com Shortcircuit if Tooltip message and richMessage are empty (flutter/flutter#182524) 2026-02-21 50643541+Mairramer@users.noreply.github.com Add fields getter to FormState (flutter/flutter#180815) 2026-02-20 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): use static whitelist for image codec tests (flutter/flutter#182648) 2026-02-20 victorsanniay@gmail.com Add cupertino docimports for CupertinoPageTransitionsBuilder and fix typos (flutter/flutter#182685) 2026-02-20 katelovett@google.com Fix Chat invite link (flutter/flutter#182675) 2026-02-20 engine-flutter-autoroll@skia.org Roll Skia from ce5854495a3a to c91ad88e89f8 (58 revisions) (flutter/flutter#182678) 2026-02-20 30870216+gaaclarke@users.noreply.github.com Manual dart sdk flutter 174bcc79 25ff 4267 8e26 d0e902f18681 1771486449 (flutter/flutter#182624) 2026-02-20 97480502+b-luk@users.noreply.github.com Don't compile shaders to SkSL unless --sksl arg is present (flutter/flutter#182519) 2026-02-20 katelovett@google.com Correct PerformanceOverlay optionsMask checks and add tests (flutter/flutter#182309) 2026-02-20 jason-simmons@users.noreply.github.com [Impeller] libImpeller: Dispose thread local caches on each Vulkan frame (flutter/flutter#182402) 2026-02-20 31859944+LongCatIsLooong@users.noreply.github.com Update CHANGELOG for 3.41.2 stable hotfix (flutter/flutter#182647) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC louisehsu@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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…ame (flutter#182402) The Impeller Vulkan back end caches command pools in thread-local storage. These caches can grow unbounded unless the embedder calls ContextVK::DisposeThreadLocalCachedResources() This PR ensures that libImpeller Vulkan apps do this on each frame by calling DisposeThreadLocalCachedResources inside the ImpellerVulkanSwapchainAcquireNextSurfaceNew API.
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…path The Impeller Vulkan backend caches command pools and descriptor pools in thread-local storage. These caches grow unbounded unless DisposeThreadLocalCachedResources() is called each frame. PRs flutter#182265 and flutter#182402 fixed this for GPUSurfaceVulkanImpeller (delegate path) and libImpeller (C API) respectively, but the Flutter Embedder API compositor path through EmbedderExternalViewEmbedder was missed. EmbedderExternalViewEmbedder::SubmitFlutterView calls builder.Render() which calls EmbedderExternalView::Render() which calls the RenderToTarget overload that does not dispose cached resources. This causes linear memory growth from leaked VkCommandBuffers (~20-40KB each) and VkDescriptorPools (~40-80KB each, one per ~80 frames). Add DisposeThreadLocalCachedResources() after builder.Render() in SubmitFlutterView, matching the pattern used in the other two paths. The call goes through the base impeller::Context interface so it is a no-op on non-Vulkan backends. Related to flutter#182265 Related to flutter#182402
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…r#11102) flutter/flutter@91b2d41...dad6f9d 2026-02-23 engine-flutter-autoroll@skia.org Roll Packages from 9da22bf to 12b43a1 (19 revisions) (flutter/flutter#182758) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 55fae1660572 to 9a5a3c92c336 (7 revisions) (flutter/flutter#182749) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 256e2b47b303 to 55fae1660572 (1 revision) (flutter/flutter#182741) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 141ed451f007 to 256e2b47b303 (1 revision) (flutter/flutter#182732) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from e59de8a12e7e to 141ed451f007 (1 revision) (flutter/flutter#182729) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from f6ea7ef42d14 to e59de8a12e7e (1 revision) (flutter/flutter#182726) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 34fa7b2373f3 to f6ea7ef42d14 (1 revision) (flutter/flutter#182721) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from 3ca547c8b816 to 34fa7b2373f3 (2 revisions) (flutter/flutter#182711) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from c91ad88e89f8 to 3ca547c8b816 (9 revisions) (flutter/flutter#182696) 2026-02-21 victorsanniay@gmail.com Shortcircuit if Tooltip message and richMessage are empty (flutter/flutter#182524) 2026-02-21 50643541+Mairramer@users.noreply.github.com Add fields getter to FormState (flutter/flutter#180815) 2026-02-20 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): use static whitelist for image codec tests (flutter/flutter#182648) 2026-02-20 victorsanniay@gmail.com Add cupertino docimports for CupertinoPageTransitionsBuilder and fix typos (flutter/flutter#182685) 2026-02-20 katelovett@google.com Fix Chat invite link (flutter/flutter#182675) 2026-02-20 engine-flutter-autoroll@skia.org Roll Skia from ce5854495a3a to c91ad88e89f8 (58 revisions) (flutter/flutter#182678) 2026-02-20 30870216+gaaclarke@users.noreply.github.com Manual dart sdk flutter 174bcc79 25ff 4267 8e26 d0e902f18681 1771486449 (flutter/flutter#182624) 2026-02-20 97480502+b-luk@users.noreply.github.com Don't compile shaders to SkSL unless --sksl arg is present (flutter/flutter#182519) 2026-02-20 katelovett@google.com Correct PerformanceOverlay optionsMask checks and add tests (flutter/flutter#182309) 2026-02-20 jason-simmons@users.noreply.github.com [Impeller] libImpeller: Dispose thread local caches on each Vulkan frame (flutter/flutter#182402) 2026-02-20 31859944+LongCatIsLooong@users.noreply.github.com Update CHANGELOG for 3.41.2 stable hotfix (flutter/flutter#182647) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC louisehsu@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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…ame (flutter#182402) The Impeller Vulkan back end caches command pools in thread-local storage. These caches can grow unbounded unless the embedder calls ContextVK::DisposeThreadLocalCachedResources() This PR ensures that libImpeller Vulkan apps do this on each frame by calling DisposeThreadLocalCachedResources inside the ImpellerVulkanSwapchainAcquireNextSurfaceNew API.
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…r#11102) flutter/flutter@91b2d41...dad6f9d 2026-02-23 engine-flutter-autoroll@skia.org Roll Packages from 9da22bf to 12b43a1 (19 revisions) (flutter/flutter#182758) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 55fae1660572 to 9a5a3c92c336 (7 revisions) (flutter/flutter#182749) 2026-02-23 engine-flutter-autoroll@skia.org Roll Skia from 256e2b47b303 to 55fae1660572 (1 revision) (flutter/flutter#182741) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 141ed451f007 to 256e2b47b303 (1 revision) (flutter/flutter#182732) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from e59de8a12e7e to 141ed451f007 (1 revision) (flutter/flutter#182729) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from f6ea7ef42d14 to e59de8a12e7e (1 revision) (flutter/flutter#182726) 2026-02-22 engine-flutter-autoroll@skia.org Roll Skia from 34fa7b2373f3 to f6ea7ef42d14 (1 revision) (flutter/flutter#182721) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from 3ca547c8b816 to 34fa7b2373f3 (2 revisions) (flutter/flutter#182711) 2026-02-21 engine-flutter-autoroll@skia.org Roll Skia from c91ad88e89f8 to 3ca547c8b816 (9 revisions) (flutter/flutter#182696) 2026-02-21 victorsanniay@gmail.com Shortcircuit if Tooltip message and richMessage are empty (flutter/flutter#182524) 2026-02-21 50643541+Mairramer@users.noreply.github.com Add fields getter to FormState (flutter/flutter#180815) 2026-02-20 1961493+harryterkelsen@users.noreply.github.com fix(web_ui): use static whitelist for image codec tests (flutter/flutter#182648) 2026-02-20 victorsanniay@gmail.com Add cupertino docimports for CupertinoPageTransitionsBuilder and fix typos (flutter/flutter#182685) 2026-02-20 katelovett@google.com Fix Chat invite link (flutter/flutter#182675) 2026-02-20 engine-flutter-autoroll@skia.org Roll Skia from ce5854495a3a to c91ad88e89f8 (58 revisions) (flutter/flutter#182678) 2026-02-20 30870216+gaaclarke@users.noreply.github.com Manual dart sdk flutter 174bcc79 25ff 4267 8e26 d0e902f18681 1771486449 (flutter/flutter#182624) 2026-02-20 97480502+b-luk@users.noreply.github.com Don't compile shaders to SkSL unless --sksl arg is present (flutter/flutter#182519) 2026-02-20 katelovett@google.com Correct PerformanceOverlay optionsMask checks and add tests (flutter/flutter#182309) 2026-02-20 jason-simmons@users.noreply.github.com [Impeller] libImpeller: Dispose thread local caches on each Vulkan frame (flutter/flutter#182402) 2026-02-20 31859944+LongCatIsLooong@users.noreply.github.com Update CHANGELOG for 3.41.2 stable hotfix (flutter/flutter#182647) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC louisehsu@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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The Impeller Vulkan back end caches command pools in thread-local storage. These caches can grow unbounded unless the embedder calls ContextVK::DisposeThreadLocalCachedResources()
This PR ensures that libImpeller Vulkan apps do this on each frame by calling DisposeThreadLocalCachedResources inside the ImpellerVulkanSwapchainAcquireNextSurfaceNew API.