Code Helper continuously runs at 400% CPU

Issue Type: Performance Issue

May have started in the latest VSCode version.

Code Helper occasionally spikes to up to 400% CPU and entire system / VS Code is unresponsive.

Extension version: 3.0.1 VS Code version: Code 1.33.1 (51b0b28134d51361cf996d2f0a1c698247aeabd8, 2019-04-11T08:22:55.268Z) OS version: Darwin x64 18.5.0

System Info

Item	Value
CPUs	Intel® Core™ i7-6920HQ CPU @ 2.90GHz (8 x 2900)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: enabled rasterization: enabled surface_synchronization: enabled_on video_decode: enabled webgl: enabled webgl2: enabled
Load (avg)	8, 6, 8
Memory (System)	16.00GB (0.47GB free)
Process Argv	packages/dashcam
Screen Reader	no
VM	0%

Process Info

CPU %	Mem MB	   PID	Process
   19	    98	 36447	code main
    0	    98	 36448	   gpu-process
    0	    82	 36449	   window (dashcam.dart — dashcam)
    0	    33	 36452	     extensionHost
    0	    33	 36456	       /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/dart /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/snapshots/analysis_server.dart.snapshot --client-id=Dart-Code.dart-code --client-version=3.0.1
    0	     0	 36457	       bash /Users/ened/dev/flutter/bin/flutter daemon
    0	    49	 36473	         /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/dart /Users/ened/dev/flutter/bin/cache/flutter_tools.snapshot daemon
    2	     0	 95528	           /bin/bash /Applications/Xcode.app/Contents/Developer/usr/bin/simctl list --json devices
    0	    33	 95529	             /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -runFirstLaunch
    0	    33	 36453	     watcherService
    0	    66	 36484	   shared-process
    0	   279	 43251	   window (dashcam_listener.dart — com.company.app)
    0	  2916	 43259	     extensionHost
    0	   508	 43263	       /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/dart /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/snapshots/analysis_server.dart.snapshot --client-id=Dart-Code.dart-code --client-version=3.0.1
    0	     0	 43264	       bash /Users/ened/dev/flutter/bin/flutter daemon
    3	    49	 43279	         /Users/ened/dev/flutter/bin/cache/dart-sdk/bin/dart /Users/ened/dev/flutter/bin/cache/flutter_tools.snapshot daemon
    0	    66	 43260	     watcherService
    0	    49	 43262	     searchService
    0	     0	 86131	     /bin/bash -l
    0	    82	 95516	   window (Issue Reporter)
    0	     0	 95530	   /bin/ps -ax -o pid=,ppid=,pcpu=,pmem=,command=

Workspace Info

|  Window (dashcam_listener.dart — com.company.app)
|  Window (dashcam.dart — dashcam)
|    Folder (com.company.app): more than 26356 files
|      File types: xml(5478) flat(4601) json(2557) png(2186) h(1629) jar(984)
|                  dart(703) plist(569) m(458) swift(439)
|      Conf files: cmake(21) launch.json(11) settings.json(5) makefile(2)
|                  package.json(1)
|    Folder (dashcam): more than 21084 files
|      File types: class(2774) flat(2760) xml(2346) swift(1447) dex(1308)
|                  jar(1108) png(971) json(962) dart(762) h(539)
|      Conf files: launch.json(11) settings.json(6);

[DanTup]

@ened I found a serious memory leak in VS Code recently, which may have contributed to this issue. It’s been fixed by the VS Code team and is shipping in v1.35 (which I believe is planned to release tomorrow - but I don’t know if it’ll slip).

https://github.com/microsoft/vscode/issues/74446

Please let me know if you’re still seeing perf issues on that release.

[DanTup]

Thanks for the traces! I had a look through, and it didn’t look too bad except for an instance showing around half a second being spent converting completions (we seem to be doing a lot of work, and the garbage collector seems to be running many times too):

It’s possible the garbage collector is running because we’re generating a lot of objects, but I also wonder if it’s running more frequently because you don’t have a lot of RAM (I can’t find anything online documenting what triggers GC in V8 to confirm this).

Could you try disabling the auto-import completions (with the dart.autoImportCompletions) and see whether it seems to make any significant difference?