MacBook Pro
Retina, 13-inch, Late 2013
Processor  2.4 GHz Intel Core i5
Memory  8 GB 1600 MHz DDR3
Graphics  Intel Iris 1536 MB
Software  OS X 10.9.5 (13F1911)

Version 65.0.3298.0 (Official Build) canary (64-bit)

This is quite strange, behaviour I saw in a bigger app and I managed to produce this much reduced test case.

Basically what should happen is every second (for 9 seconds) it should draw a bar (consisting of rects) that should grow a bit every time to the left.  However in canary it jumps back and forth, and sometimes even loops for a while.  See attached "canvas bug canary.mov" for an example of the bad behaviour in canary, and "canvas bug normal.mov" for the correct behaviour (from Version 63.0.3239.84 (Official Build) (64-bit)).

My only guess was, because I am not using RAF, it is somehow incorrectly recycling old buffers.  Even though I know it's the modern/better way to use RAF, I don't see how anyway this wouldn't be a bug.

about:gpu

Graphics Feature Status
Canvas: Hardware accelerated
CheckerImaging: Disabled
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Hardware accelerated
Rasterization: Software only, hardware acceleration unavailable
Video Decode: Hardware accelerated
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
add_and_true_to_loop_condition
adjust_src_dst_region_for_blitframebuffer
avoid_stencil_buffers
decode_encode_srgb_for_generatemipmap
disable_av_sample_buffer_display_layer
disable_framebuffer_cmaa
disable_webgl_rgb_multisampling_usage
emulate_abs_int_function
get_frag_data_info_bug
init_one_cube_map_level_before_copyteximage
msaa_is_slow
pack_parameters_workaround_with_pack_buffer
rebind_transform_feedback_before_resume
regenerate_struct_names
remove_invariant_and_centroid_for_essl3
reset_base_mipmap_level_before_texstorage
rewrite_do_while_loops
rewrite_float_unary_minus_operator
rewrite_texelfetchoffset_to_texelfetch
scalarize_vec_and_mat_constructor_args
set_zero_level_before_generating_mipmap
unfold_short_circuit_as_ternary_operation
unpack_alignment_workaround_with_unpack_buffer
unpack_image_height_workaround_with_unpack_buffer
use_intermediary_for_copy_texture_image
use_shadowed_tex_level_params
use_unused_standard_shared_blocks
validate_multisample_buffer_allocation
Problems Detected
There are display issues with GPU Raster on OSX 10.9: 611310
Disabled Features: gpu_rasterization
Multisampled renderbuffer allocation must be validated on some Macs: 290391
Applied Workarounds: validate_multisample_buffer_allocation
Unfold short circuit on Mac OS X: 307751
Applied Workarounds: unfold_short_circuit_as_ternary_operation
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
Mac drivers handle struct scopes incorrectly: 403957
Applied Workarounds: regenerate_struct_names
On Intel GPUs MSAA performance is not acceptable for GPU rasterization: 527565
Applied Workarounds: msaa_is_slow
glGenerateMipmap fails if the zero texture level is not set on some Mac drivers: 560499
Applied Workarounds: set_zero_level_before_generating_mipmap
Pack parameters work incorrectly with pack buffer bound: 563714
Applied Workarounds: pack_parameters_workaround_with_pack_buffer
Alignment works incorrectly with unpack buffer bound: 563714
Applied Workarounds: unpack_alignment_workaround_with_unpack_buffer
copyTexImage2D fails when reading from IOSurface on multiple GPU types.: 581777
Applied Workarounds: use_intermediary_for_copy_texture_image
Multisample renderbuffers with format GL_RGB8 have performance issues on Intel GPUs.: 607130
Applied Workarounds: disable_webgl_rgb_multisampling_usage
Mac Drivers store texture level parameters on int16_t that overflow: 610153
Applied Workarounds: use_shadowed_tex_level_params
Use GL_INTEL_framebuffer_CMAA on ChromeOS: 535198
Applied Workarounds: disable_framebuffer_cmaa
glGetFragData{Location|Index} works incorrectly on Max: 638340
Applied Workarounds: get_frag_data_info_bug
glResumeTransformFeedback works incorrectly on Intel GPUs: 638514
Applied Workarounds: rebind_transform_feedback_before_resume
glTexStorage* are buggy when base mipmap level is not 0: 640506
Applied Workarounds: reset_base_mipmap_level_before_texstorage
Result of abs(i) where i is an integer in vertex shader is wrong: 642227
Applied Workarounds: emulate_abs_int_function
Rewrite texelFetchOffset to texelFetch for Intel Mac: 642605
Applied Workarounds: rewrite_texelfetchoffset_to_texelfetch
Rewrite condition in for and while loops for Intel Mac: 644669
Applied Workarounds: add_and_true_to_loop_condition
Rewrite do-while loops to simpler constructs on Mac: 644669
Applied Workarounds: rewrite_do_while_loops
AVSampleBufferDisplayLayer leaks IOSurfaces on 10.9.: 632178
Applied Workarounds: disable_av_sample_buffer_display_layer
Do TexImage2D first before CopyTexImage2D for cube map texture on Intel Mac 10.11: 648197
Applied Workarounds: init_one_cube_map_level_before_copyteximage
Decode and encode before generateMipmap for srgb format textures on macosx: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
Insert statements to reference all members in unused std140/shared blocks on Mac: 618464
Applied Workarounds: use_unused_standard_shared_blocks
Tex(Sub)Image3D performs incorrectly when uploading from unpack buffer with GL_UNPACK_IMAGE_HEIGHT greater than zero on Intel Macs: 654258
Applied Workarounds: unpack_image_height_workaround_with_unpack_buffer
adjust src/dst region if blitting pixels outside read framebuffer on Mac: 644740
Applied Workarounds: adjust_src_dst_region_for_blitframebuffer
Mac driver GL 4.1 requires invariant and centroid to match between shaders: 639760, 641129
Applied Workarounds: remove_invariant_and_centroid_for_essl3
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Applied Workarounds: disable(GL_KHR_blend_equation_advanced), disable(GL_KHR_blend_equation_advanced_coherent)
Rewrite -float to 0.0 - float for Intel Mac: 672380
Applied Workarounds: rewrite_float_unary_minus_operator
Certain Apple devices leak stencil buffers: 713854
Applied Workarounds: avoid_stencil_buffers
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	12/19/2017, 12:12:30 AM
Chrome version	Chrome/65.0.3298.0
Operating system	Mac OS X 10.9.5
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/6586a208880a70a00856529493741971ecfea5c2/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/6586a208880a70a00856529493741971ecfea5c2/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	647dca7672f7
2D graphics backend	Skia/65 ef0384835757df463f5157145650a60ba8b14a63-
Command Line	/Applications/Google Chrome Canary.app/Contents/MacOS/Google Chrome Canary --flag-switches-begin --enable-devtools-experiments --flag-switches-end
Driver Information
Initialization time	40
In-process GPU	false
Passthrough Command Decoder	false
Direct Composition	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0x0a2e *ACTIVE*
Optimus	false
Optimus	false
AMD switchable	false
Driver vendor	
Driver version	8.28.37
Driver date	
Pixel shader version	4.10
Vertex shader version	4.10
Max. MSAA samples	8
Machine model name	MacBookPro
Machine model version	11.1
GL_VENDOR	Intel Inc.
GL_RENDERER	Intel Iris OpenGL Engine
GL_VERSION	4.1 INTEL-8.28.37
GL_EXTENSIONS	GL_ARB_blend_func_extended GL_ARB_draw_buffers_blend GL_ARB_draw_indirect GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location GL_ARB_gpu_shader_fp64 GL_ARB_gpu_shader5 GL_ARB_instanced_arrays GL_ARB_internalformat_query GL_ARB_occlusion_query2 GL_ARB_sample_shading GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding GL_ARB_shader_subroutine GL_ARB_shading_language_include GL_ARB_tessellation_shader GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_cube_map_array GL_ARB_texture_gather GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query GL_ARB_transform_feedback2 GL_ARB_transform_feedback3 GL_ARB_vertex_attrib_64bit GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_framebuffer_multisample_blit_scaled GL_EXT_texture_compression_s3tc GL_EXT_texture_filter_anisotropic GL_EXT_texture_sRGB_decode GL_APPLE_client_storage GL_APPLE_container_object_shareable GL_APPLE_flush_render GL_APPLE_object_purgeable GL_APPLE_rgb_422 GL_APPLE_row_bytes GL_APPLE_texture_range GL_ATI_texture_mirror_once GL_NV_texture_barrier
Disabled Extensions	GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Window system binding vendor	
Window system binding version	
Window system binding extensions	
Direct rendering	Yes
Reset notification strategy	0x0000
GPU process crash count	0
Compositor Information
Tile Update Mode	Zero-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	GPU_READ, SCANOUT, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
R_16	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	Software only
RGBA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRX_1010102	Software only
BGRA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RGBA_F16	GPU_READ, SCANOUT, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
YVU_420	Software only
YUV_420_BIPLANAR	GPU_READ, SCANOUT, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
UYVY_422	GPU_READ, SCANOUT, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
Display(s) Information
Info	Display[69732352] bounds=0,0 1280x800, workarea=0,22 1280x774, scale=2, external
Color space information	{primaries:BT709, transfer:IEC61966_2_1, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information
Decode h264 baseline	up to 4096x2160 pixels
Decode h264 extended	up to 4096x2160 pixels
Decode h264 main	up to 4096x2160 pixels
Decode h264 high	up to 4096x2160 pixels
Encode h264 baseline	up to 4096x2160 pixels and/or 30.000 fps
Encode h264 main	up to 4096x2160 pixels and/or 30.000 fps
Encode h264 high	up to 4096x2160 pixels and/or 30.000 fps

 

Deleted: canvas bug canary.mov 680 KB

canvas bug canary.mov 680 KB Download

Deleted: canvas bug normal.mov 360 KB

canvas bug normal.mov 360 KB Download

Deleted: canvas-bug.html 2.6 KB

canvas-bug.html 2.6 KB View Download