[Impeller] Started tracking the pool with the command buffer. #45298

gaaclarke · 2023-08-30T20:17:40Z

issue: flutter/flutter#133506

This fixes one of the issues seen in flutter/flutter#133506. There were multiple ones though.

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I listed at least one issue that this PR fixes in the description above.
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impeller/renderer/backend/vulkan/command_encoder_vk.cc

gaaclarke · 2023-08-31T19:37:45Z

impeller/renderer/backend/vulkan/resource_manager_vk.h

  std::mutex reclaimables_mutex_;
  std::condition_variable reclaimables_cv_;
  Reclaimables reclaimables_;
  bool should_exit_ = false;
+  // This should be initialized last since it references the other instance
+  // variables.
+  std::thread waiter_;


This is just a nasty race condition I was running into.

matanlurey

Defer explicit approval to someone else since I'm just getting started here, but thanks!

impeller/renderer/backend/vulkan/command_encoder_vk.cc

gaaclarke · 2023-09-06T22:11:58Z

@chinmaygarde friendly ping

jonahwilliams · 2023-09-07T18:26:37Z

impeller/renderer/backend/vulkan/command_encoder_vk_unittests.cc

+namespace impeller {
+namespace testing {
+
+TEST(CommandEncoderVKTest, DeleteEncoderAfterThreadDies) {


I have sort of mixed feelings about these tests, because its sort disjointed from how these classes are used. I would feel better if there was substantially more commentary on specifically what these tests are covering.

Or at least for one of them, and then subsequent tests could have less commentary.

Unit tests are supposed to be testing how a class can be used, not how they are supposed to be used. Maybe it will help to understand why I implemented this fix. The pool change is a fix for a real bug that I was running into when using the playgrounds test harness which Chinmay was trying to get working. So, it may be true that this bug shouldn't present itself in production, it has demonstrably happened in our test harness and may present itself accidentally in production.

The second fix with the resourcemanager is definitely something that can manifest in production code, but was showing up regularly in these tests.

We typically don't annotate unit tests that are using the public api of a method. I'm happy to add any comments you think will help.

I understand that, what I'm saying is that I'm having a hard time following the test and so I'd appreciate more commentary on how/why the particular test successfully exercises the assertions.

I added a comment to the first test, expanded the second comment and removed one piece of vestigial code.

jonahwilliams

So today the current implementation with a weak_ptr is safe because we actually never actually clean up a cmd pool, we just recycle the same one over and over again.

Of course, if we start trying to recycle the cmd pools this might become a problem, but that problem might be different?

if the cmd encoder has a strong reference to the cmd pool, this won't cause retention cycles right? because the pool doesn't have a strong reference to the impeller::vk classes.

So thinking out loud I think this is safe

gaaclarke · 2023-09-07T20:00:44Z

So today the current implementation with a weak_ptr is safe because we actually never actually clean up a cmd pool, we just recycle the same one over and over again.

This was manifesting in the playgrounds test harness, not in production apps. (mentioned above)

Of course, if we start trying to recycle the cmd pools this might become a problem, but that problem might be different?

if the cmd encoder has a strong reference to the cmd pool, this won't cause retention cycles right? because the pool doesn't have a strong reference to the impeller::vk classes.

The other shared_ptr for the pool lives on the static thread_local storage, the pool doesn't have a strong reference to that so that shouldn't be a cycle.

So thinking out loud I think this is safe

Yep, I believe so.

jonahwilliams

LGTM. Ask for comments is just a nit.

…r. (flutter/engine#45298)

…134249) flutter/engine@2dba8ce...a828c26 2023-09-07 skia-flutter-autoroll@skia.org Roll ANGLE from 204c07a56b64 to cdbc45a9f37e (1 revision) (flutter/engine#45551) 2023-09-07 skia-flutter-autoroll@skia.org Roll Fuchsia Mac SDK from WbB3tmMXnuwJBAHoi... to EuBfOtm5TZIdgNaQe... (flutter/engine#45550) 2023-09-07 skia-flutter-autoroll@skia.org Roll Skia from ee741e5e8cf3 to ce2c94883cb5 (1 revision) (flutter/engine#45552) 2023-09-07 30870216+gaaclarke@users.noreply.github.com [Impeller] Started tracking the pool with the command buffer. (flutter/engine#45298) 2023-09-07 49699333+dependabot[bot]@users.noreply.github.com Bump actions/checkout from 3.6.0 to 4.0.0 (flutter/engine#45439) 2023-09-07 41930132+hellohuanlin@users.noreply.github.com Reverts part of "fix auto-correction highlight on top left corner (Again)" (flutter/engine#45523) 2023-09-07 skia-flutter-autoroll@skia.org Roll Skia from 59a2610cd83d to ee741e5e8cf3 (4 revisions) (flutter/engine#45548) 2023-09-07 skia-flutter-autoroll@skia.org Roll ANGLE from 60b56591dee5 to 204c07a56b64 (7 revisions) (flutter/engine#45546) Also rolling transitive DEPS: fuchsia/sdk/core/mac-amd64 from WbB3tmMXnuwJ to EuBfOtm5TZId If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll Please CC rmistry@google.com,zra@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

github-actions bot added the e: impeller label Aug 30, 2023

gaaclarke mentioned this pull request Aug 30, 2023

[Impeller] Validation errors when running playgrounds with Vulkan validation enabled. flutter/flutter#133506

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chinmaygarde changed the title ~~[Impeller] started tracking the pool with the command buffer~~ [Impeller] Started tracking the pool with the command buffer. Aug 31, 2023

chinmaygarde assigned gaaclarke Aug 31, 2023

gaaclarke commented Aug 31, 2023

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gaaclarke force-pushed the track-command-pool branch from 5ca3faa to 1d680e4 Compare August 31, 2023 19:39

gaaclarke marked this pull request as ready for review August 31, 2023 19:45

gaaclarke requested review from chinmaygarde and matanlurey August 31, 2023 19:45

matanlurey reviewed Aug 31, 2023

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jonahwilliams reviewed Sep 7, 2023

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gaaclarke added 5 commits September 7, 2023 12:46

[Impeller] started tracking the pool with the command buffer

4f4240d

added test

0f47509

added second test

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updated licenses

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added comment

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gaaclarke force-pushed the track-command-pool branch from 802956a to 30b3b3d Compare September 7, 2023 19:51

jonahwilliams approved these changes Sep 7, 2023

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expanded and simplified test

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gaaclarke added the autosubmit Merge PR when tree becomes green via auto submit App label Sep 7, 2023

auto-submit bot merged commit 1bc18ff into flutter:main Sep 7, 2023
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engine-flutter-autoroll mentioned this pull request Sep 7, 2023

Roll Flutter Engine from 2dba8ceca824 to a828c26e7e97 (8 revisions) flutter/flutter#134249

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/flutter that referenced this pull request Sep 7, 2023

1bc18ffeb [Impeller] Started tracking the pool with the command buffe…

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…r. (flutter/engine#45298)

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[Impeller] Started tracking the pool with the command buffer. #45298

[Impeller] Started tracking the pool with the command buffer. #45298

gaaclarke commented Aug 30, 2023 •

edited

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[Impeller] Started tracking the pool with the command buffer. #45298

[Impeller] Started tracking the pool with the command buffer. #45298

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gaaclarke commented Aug 30, 2023 • edited

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edited