## Description
As the related issue refer, the application may be doing too much work on its main thread even in a simple hello_world demo.
That is because the creation of `Engine` on the ui thread takes a noticeable time, and it is blocking the platform thread in order to run `Shell::Setup` synchronously.
The cost of `Engine`'s constructor is mainly about the creating of root isolate. Actually, there used to be another time-consuming process, the default font manager setup, which was resolved by https://github.com/flutter/engine/pull/18225.
Similar to https://github.com/flutter/engine/pull/18225, this pr move the creation of root isolate out from creating `Engine`. After this action, the main thread blocking is quite an acceptable slice.
## Related Issues
https://github.com/flutter/flutter/issues/40563 could be resolved by this pr.
Reland #19396 with a fix for improper scale that was affecting internal tests
Tested: Ran all unittests, ran internal tests, and ran workstation on Fuchsia
BUG: 53062, 53063
The fuchsia code around metrics and sizing was just sending this
information through a side-channel, when the engine already had the
information available. So, delete all of it to make future CLs simpler.
Additionally, the SceneUpdateContext has many unneccesary dependencies
re: metrics and PaintTasks. Break those to make future CLs simpler.
Tested: Ran all unittests and ran workstation on Fuchsia
BUG: 53062, 53063
This reverts commit 6ea69a0d4339dd153899bb6c299689f1dd43329d.
On top of the revert, it reverted a commit in the PR:
https://github.com/flutter/engine/pull/14024
This reverts commit ea67e5b0b930ebf552bc7dbd678a35ee6a129c39.
Remove dead shared snapshot arguments to Dart_CreateIsolateGroup.
6a65ea9cad4b [vm] Remove shared snapshot and reused instructions features.
db8370e36147 [gardening] Fix frontend-server dartdevc windows test.
4601bd7bffea Modified supertype check error message to be more descriptive.
0449905e2de6 [CFE] Add a serialization-and-unserialization step to strong test
c8b903c2f94f Update CHANGELOG.md
2a12a13d9684 [Test] Skips emit_aot_size_info_flag_test on crossword.
b26127fe01a5 [cfe] Add reachability test skeleton
Obtaining the SkiaUnrefQueue through the IOManager is unsafe because
UIDartState has a weak pointer to the IOManager that can not be dereferenced
on the UI thread.
The contents rendered into the backing stores are already correctly scaled.
The initial implementation assumed this also held true for the metrics obtained
via embedded view parameters.
Fixes b/142699417
Since this is currently only meant to be used by the embedding internally, the setter in Objective-C is only exposed via the FlutterDartProject private class extension. Unit tests have been added to the shell_unittests harness.
Fixes https://github.com/flutter/flutter/issues/37641
This reverts commit c2879cae2ee3707ad07af1118bf4862dc1d82bb7.
Additionally, we fix https://github.com/flutter/flutter/issues/40863 by adding a secondary VSYNC callback.
Unit tests are updated to provide VSYNC mocking and check the fix of https://github.com/flutter/flutter/issues/40863.
The root cause of having https://github.com/flutter/flutter/issues/40863 is the false assumption that each input event must trigger a new frame. That was true in the framework PR https://github.com/flutter/flutter/pull/36616 because the input events there are all scrolling move events. When the PR was ported to the engine, we can no longer distinguish different types of events, and tap events may no longer trigger a new frame.
Therefore, this PR directly hooks into the `VsyncWaiter` and uses its (newly added) secondary callback to dispatch the pending input event.
This reverts commit fcc4ab32301396986dd5103d6d444bff35fe0f63.
Fixes https://github.com/flutter/flutter/issues/41394 and other
related correctness issues.
TBR: @arbreng @jason-simmons @mehmetf
On Fuchsia, add a build flag for compositing OpacityLayers using the system
compositor vs Skia, which exposes a fastpath for opacity via Scenic.
This will only work under certain circumstances, in particular nested
OpacityLayers will not render correctly!
On Fuchsia, add a build flag for compositing PhysicalShapeLayers using
the system compositor vs Skia. Set to off by default, which restores
performant shadows on Fuchsia.
Remove the opacity exposed from ChildView, as that was added mistakenly.
Finally, we centralize the logic for switching between the
system-composited and in-process-composited paths inside of
ContainerLayer. We also centralize the logic for computing elevation
there. This allows the removal of many OS_FUCHSIA-specific code-paths.
Test: Ran workstation on Fuchsia; benchmarked before and after
Bug: 23711
Bug: 24163
* Fix broken tests
Additionally, we now use the engine directly as a delegate instead of storing potentially dead runtime_controller.
Unit tests have been updated to include an engine restart check which would fail before the fix.
This fixes https://github.com/flutter/flutter/issues/40303
The engine's activity_running flag tracks whether the app is in the paused or
running lifecycle state. The engine had been defaulting activity_running to
false (meaning paused). But the animator had been defaulting its paused flag
to false, which allowed frames to render at startup. If the engine loses and
regains its surface, then frames would stop rendering because activity_running
is false (even though frames had been rendering when the engine initially
acquired its surface).
This change puts the engine and the animator into a consistent state at
startup. Frames will continue to render until the embedder sends a lifecycle
message that will pause both the engine and the animator.
See https://github.com/flutter/flutter/issues/32624
This patch reworks image decompression and collection in the following ways
because of misbehavior in the described edge cases.
The current flow for realizing a texture on the GPU from a blob of compressed
bytes is to first pass it to the IO thread for image decompression and then
upload to the GPU. The handle to the texture on the GPU is then passed back to
the UI thread so that it can be included in subsequent layer trees for
rendering. The GPU contexts on the Render & IO threads are in the same
sharegroup so the texture ends up being visible to the Render Thread context
during rendering. This works fine and does not block the UI thread. All
references to the image are owned on UI thread by Dart objects. When the final
reference to the image is dropped, the texture cannot be collected on the UI
thread (because it has not GPU context). Instead, it must be passed to either
the GPU or IO threads. The GPU thread is usually in the middle of a frame
workload so we redirect the same to the IO thread for eventual collection. While
texture collections are usually (comparatively) fast, texture decompression and
upload are slow (order of magnitude of frame intervals).
For application that end up creating (by not necessarily using) numerous large
textures in straight-line execution, it could be the case that texture
collection tasks are pending on the IO task runner after all the image
decompressions (and upload) are done. Put simply, the collection of the first
image could be waiting for the decompression and upload of the last image in the
queue.
This is exacerbated by two other hacks added to workaround unrelated issues.
* First, creating a codec with a single image frame immediately kicks of
decompression and upload of that frame image (even if the frame was never
request from the codec). This hack was added because we wanted to get rid of
the compressed image allocation ASAP. The expectation was codecs would only be
created with the sole purpose of getting the decompressed image bytes.
However, for applications that only create codecs to get image sizes (but
never actually decompress the same), we would end up replacing the compressed
image allocation with a larger allocation (device resident no less) for no
obvious use. This issue is particularly insidious when you consider that the
codec is usually asked for the native image size first before the frame is
requested at a smaller size (usually using a new codec with same data but new
targetsize). This would cause the creation of a whole extra texture (at 1:1)
when the caller was trying to “optimize” for memory use by requesting a
texture of a smaller size.
* Second, all image collections we delayed in by the unref queue by 250ms
because of observations that the calling thread (the UI thread) was being
descheduled unnecessarily when a task with a timeout of zero was posted from
the same (recall that a task has to be posted to the IO thread for the
collection of that texture). 250ms is multiple frame intervals worth of
potentially unnecessary textures.
The net result of these issues is that we may end up creating textures when all
that the application needs is to ask it’s codec for details about the same (but
not necessarily access its bytes). Texture collection could also be delayed
behind other jobs to decompress the textures on the IO thread. Also, all texture
collections are delayed for an arbitrary amount of time.
These issues cause applications to be susceptible to OOM situations. These
situations manifest in various ways. Host memory exhaustion causes the usual OOM
issues. Device memory exhaustion seems to manifest in different ways on iOS and
Android. On Android, allocation of a new texture seems to be causing an
assertion (in the driver). On iOS, the call hangs (presumably waiting for
another thread to release textures which we won’t do because those tasks are
blocked behind the current task completing).
To address peak memory usage, the following changes have been made:
* Image decompression and upload/collection no longer happen on the same thread.
All image decompression will now be handled on a workqueue. The number of
worker threads in this workqueue is equal to the number of processors on the
device. These threads have a lower priority that either the UI or Render
threads. These workers are shared between all Flutter applications in the
process.
* Both the images and their codec now report the correct allocation size to Dart
for GC purposes. The Dart VM uses this to pick objects for collection. Earlier
the image allocation was assumed to 32bpp with no mipmapping overhead
reported. Now, the correct image size is reported and the mipmapping overhead
is accounted for. Image codec sizes were not reported to the VM earlier and
now are. Expect “External” VM allocations to be higher than previously
reported and the numbers in Observatory to line up more closely with actual
memory usage (device and host).
* Decoding images to a specific size used to decode to 1:1 before performing a
resize to the correct dimensions before texture upload. This has now been
reworked so that images are first decompressed to a smaller size supported
natively by the codec before final resizing to the requested target size. The
intermediate copy is now smaller and more promptly collected. Resizing also
happens on the workqueue worker.
* The drain interval of the unref queue is now sub-frame-interval. I am hesitant
to remove the delay entirely because I have not been able to instrument the
performance overhead of the same. That is next on my list. But now, multiple
frame intervals worth of textures no longer stick around.
The following issues have been addressed:
* https://github.com/flutter/flutter/issues/34070 Since this was the first usage
of the concurrent message loops, the number of idle wakes were determined to
be too high and this component has been rewritten to be simpler and not use
the existing task runner and MessageLoopImpl interface.
* Image decoding had no tests. The new `ui_unittests` harness has been added
that sets up a GPU test harness on the host using SwiftShader. Tests have been
added for image decompression, upload and resizing.
* The device memory exhaustion in this benchmark has been addressed. That
benchmark is still not viable for inclusion in any harness however because it
creates 9 million codecs in straight-line execution. Because these codecs are
destroyed in the microtask callbacks, these are referenced till those
callbacks are executed. So now, instead of device memory exhaustion, this will
lead to (slower) exhaustion of host memory. This is expected and working as
intended.
This patch only addresses peak memory use and makes collection of unused images
and textures more prompt. It does NOT address memory use by images referenced
strongly by the application or framework.
