Type: Performance Issue
Behaviour
pytest runner in the left panel seems to do something like dist=load despite my settings.json, resulting in periodic bottlenecking on slow tests.
Steps to reproduce:
Running my large suite with uv run pytest tests -n auto --dist worksteal saturates CPU and gives long ..... lines undifferentiated by filenames. But execting the runner with settings.json
{
"python.testing.pytestArgs": [
"tests",
"-n", "auto",
"--dist", "worksteal"
],
"python.testing.unittestEnabled": false,
"python.testing.pytestEnabled": true
}produces a long list of FILENAME ..... [PCT%] lines, and repeated bursts of full core saturation interspersed by long stretches of single-core usage in a single suite run.
Diagnostic data
Details
Excerpt from the TEST RESULTS panel:
Running pytest with args: ['-p', 'vscode_pytest', '-n', 'auto', '--dist', 'worksteal', '--rootdir=/home/tbertalan/lake/Projects/ModelCalibration-issue-118', (long list of specific path/file.py::class entries snipped here)
============================= test session starts ==============================
platform linux -- Python 3.12.13, pytest-9.0.3, pluggy-1.6.0
rootdir: /home/tbertalan/lake/Projects/ModelCalibration-issue-118
configfile: pyproject.toml
plugins: cov-7.1.0, xdist-3.8.0, typeguard-2.13.3, jaxtyping-0.3.11, anyio-4.13.0
collected 446 items
tests/test_anp_loader.py ........................................ [ 8%]
tests/test_anp_registry.py .............................. [ 15%]
tests/test_behavior.py ....... [ 17%]
vs a (non-vscode) terminal run
tbertalan@swiftie:~/lake/Projects/ModelCalibration-issue-118$ uv run pytest -n auto -p no:slow-first
Built modelcalibration @ file:///home/tbertalan/lake/Projects/ModelCalibration-issue-118
Uninstalled 1 package in 0.81ms
Installed 1 package in 3ms
============================================================================================== test session starts ==============================================================================================
platform linux -- Python 3.12.13, pytest-9.0.3, pluggy-1.6.0
rootdir: /home/tbertalan/lake/Projects/ModelCalibration-issue-118
configfile: pyproject.toml
testpaths: tests
plugins: cov-7.1.0, xdist-3.8.0, typeguard-2.13.3, jaxtyping-0.3.11, anyio-4.13.0
4 workers [446 items]
...............................................................................................................................................................x.xxx............................x........ [ 45%]
.................x..x.....................................................................Xss............................................................................................................ [ 90%]
............................................
Extension version: 2026.4.0
VS Code version: Code 1.129.1 (8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8, 2026-07-17T15:35:09Z)
OS version: Windows_NT x64 10.0.26200
Modes:
Remote OS version: Linux x64 6.14.0-37-generic
- Python version (& distribution if applicable, e.g. Anaconda): 3.13.3.final.0
- Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): System
- Value of the
python.languageServer setting: Default
User Settings
languageServer: "Pylance"
testing
• pytestArgs: "<placeholder>"
• pytestEnabled: true
Installed Extensions
| Extension Name |
Extension Id |
Version |
| autopep8 |
ms- |
2026.4.0 |
| claude-code |
Ant |
2.1.215 |
| copilot-chat |
Git |
0.57.0 |
| debugpy |
ms- |
2026.6.0 |
| git-graph |
mhu |
1.30.0 |
| git-worktrees |
Git |
2.16.0 |
| js-debug |
ms- |
1.117.0 |
| jsts-chat-features |
Typ |
0.0.4 |
| jupyter |
ms- |
2025.9.1 |
| jupyter-renderers |
ms- |
1.3.0 |
| markdown-all-in-one |
yzh |
3.6.3 |
| markdown-mermaid |
bie |
1.32.1 |
| mypy-type-checker |
ms- |
2026.6.0 |
| pth-viewer |
pth |
0.0.12 |
| pylint |
ms- |
2026.6.0 |
| python |
ms- |
2026.4.0 |
| rainbow-csv |
mec |
3.24.1 |
| vscode-js-profile-table |
ms- |
1.0.10 |
| vscode-jupyter-cell-tags |
ms- |
0.1.9 |
| vscode-jupyter-slideshow |
ms- |
0.1.6 |
| vscode-markdownlint |
Dav |
0.61.2 |
| vscode-pull-request-github |
Git |
0.158.0 |
| vscode-pylance |
ms- |
2026.2.1 |
| vscode-python-envs |
ms- |
1.36.0 |
| webm-preview |
gso |
0.1.2 |
System Info
| Item |
Value |
| CPUs |
AMD Ryzen 5 7530U with Radeon Graphics (12 x 1996) |
| GPU Status |
2d_canvas: enabled
GPU0: VENDOR= 0x1002, DEVICE=0x15e7 [AMD Radeon (TM) Graphics], DRIVER_VENDOR=AMD, DRIVER_VERSION=31.0.21923.13006 ACTIVE
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8875
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off |
| Load (avg) |
undefined |
| Memory (System) |
14.83GB (0.10GB free) |
| Process Argv |
--crash-reporter-id 3819bd9c-9640-441a-b637-f0405bc1724f |
| Screen Reader |
no |
| VM |
0% |
| Item |
Value |
| Remote |
SSH: swiftie |
| OS |
Linux x64 6.14.0-37-generic |
| CPUs |
Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz (8 x 4200) |
| Memory (System) |
30.28GB (18.76GB free) |
| VM |
0% |
Process Info
CPU % Mem MB PID Process
1 154 5568 code
1 599 4812 window [2] (settings.json - ModelCalibration-issue-118 [SSH: swiftie] - Visual Studio Code)
0 295 6100 window [1] (tasks.json - Journal - Visual Studio Code)
0 24 8216 crashpad-handler
0 42 17384 utility-network-service
0 476 18044 extension-host [2]
0 8 28028 C:\WINDOWS\system32\wsl.exe -d Ubuntu -e /bin/sh -c "cd '/mnt/c/Users/Tom Bertalan/AppData/Local/Programs/Microsoft VS Code' && /bin/sh"
0 13 10976 C:\WINDOWS\system32\wsl.exe -d Ubuntu -e /bin/sh -c "cd '/mnt/c/Users/Tom Bertalan/AppData/Local/Programs/Microsoft VS Code' && /bin/sh"
0 12 8400 --distro-id {0eceac0a-0de7-44db-ab7e-a953bbca12d9} --vm-id {97cfd741-f0f7-4580-b40a-526ebdaf3204} --handle 728 --event 752 --parent 756
0 10 27972 C:\WINDOWS\system32\conhost.exe 0x4
0 8 15480 C:\WINDOWS\system32\conhost.exe 0x4
0 102 23492 pty-host
0 87 2248 C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -noexit -command "try { . \"c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\out\vs\workbench\contrib\terminal\common\scripts\shellIntegration.ps1\" } catch {}"
0 12 16552 "c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\node_modules.asar.unpacked\node-pty\build\Release\conpty\OpenConsole.exe" --headless --inheritcursor --width 80 --height 30 --signal 0x55c --server 0x54c
0 12 26416 "c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\node_modules.asar.unpacked\node-pty\build\Release\conpty\OpenConsole.exe" --headless --width 80 --height 30 --signal 0x738 --server 0x730
0 91 26528 C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -noexit -command "try { . \"c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\out\vs\workbench\contrib\terminal\common\scripts\shellIntegration.ps1\" } catch {}"
0 8 31012 C:\WINDOWS\System32\cmd.exe /c (type "C:\Users\TOMBER~1\AppData\Local\Temp\vscode-linux-multi-line-command-swiftie-908041203.sh" | "C:\WINDOWS\System32\OpenSSH\ssh.exe" -T -D 57373 swiftie sh) & exit /b 0
0 14 30288 "C:\WINDOWS\System32\OpenSSH\ssh.exe" -T -D 57373 swiftie sh
0 12 34920 "c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\node_modules.asar.unpacked\node-pty\build\Release\conpty\OpenConsole.exe" --headless --inheritcursor --width 131 --height 30 --signal 0x62c --server 0x624
1 138 24056 gpu-process
0 359 28444 extension-host [1]
0 66 10424 "C:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\Code.exe" "c:\Users\Tom Bertalan\AppData\Local\Programs\Microsoft VS Code\8a7abeba6e\resources\app\extensions\json-language-features\server\dist\node\jsonServerMain" --node-ipc --clientProcessId=28444
0 388 24684 electron-nodejs (bundle.js)
0 60 30452 electron-nodejs (server.js)
0 66 34296 "C:\Users\Tom Bertalan\AppData\Roaming\uv\python\cpython-3.14.4-windows-x86_64-none\python.exe" "c:\Users\Tom Bertalan\.vscode\extensions\ms-python.pylint-2026.6.0\bundled\tool\lsp_server.py"
0 8 16588 C:\WINDOWS\system32\conhost.exe 0x4
0 12 35728 "c:\Users\Tom Bertalan\.vscode\extensions\ms-python.vscode-python-envs-1.36.0-win32-x64\python-env-tools\bin\pet.exe" server
0 7 30724 C:\WINDOWS\system32\conhost.exe 0x4
0 73 33612 file-watcher [2]
0 86 34496 file-watcher [1]
0 98 35620 shared-process
Remote: SSH: swiftie
CPU % Mem MB PID Process
2 217 1071813 remote-server
0 62 1071850 ptyHost
0 0 1071983 /bin/bash --init-file /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/out/vs/workbench/contrib/terminal/common/scripts/shellIntegration-bash.sh
0 0 1072407 /bin/bash --init-file /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/out/vs/workbench/contrib/terminal/common/scripts/shellIntegration-bash.sh
1 744 1071856 extension-host
0 62 1072004 /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/node /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/extensions/markdown-language-features/dist/serverWorkerMain --node-ipc --clientProcessId=1071856
0 155 1072022 /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/node /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/extensions/json-language-features/server/dist/node/jsonServerMain --node-ipc --clientProcessId=1071856
0 0 1072137 /home/tbertalan/.vscode-server/extensions/ms-python.vscode-python-envs-1.36.0-linux-x64/python-env-tools/bin/pet server
0 31 1072423 /home/tbertalan/lake/Projects/ModelCalibration-issue-118/.venv/bin/python /home/tbertalan/.vscode-server/extensions/ms-python.autopep8-2026.4.0/bundled/tool/lsp_server.py
0 527 1072802 /home/tbertalan/.vscode-server/cli/servers/Stable-8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8/server/node /home/tbertalan/.vscode-server/extensions/ms-python.vscode-pylance-2026.2.1/dist/server.bundle.js --cancellationReceive=file:bbb338299e1c2b081336cb52f5953bc490540afe89 --node-ipc --clientProcessId=1071856
0 62 1071873 fileWatcher
0 0 1073210 /bin/sh -c /usr/bin/ps -ax -o pid=,ppid=,pcpu=,pmem=,command=
0 0 1073211 /usr/bin/ps -ax -o pid=,ppid=,pcpu=,pmem=,command=
Workspace Info
| Window (tasks.json - Journal - Visual Studio Code)
| Folder (Journal): 229 files
| File types: json(134) md(84) png(4) pdf(3) jpg(1) py(1) gitignore(1)
| TAG(1)
| Conf files: tasks.json(1)
| Remote: SSH: swiftie| Folder (ModelCalibration-issue-118): more than 20000 files| File types: py(7391) pyi(5593) json(3018) pyc(1420) dat(1084) so(159)
| txt(132) typed(61) md(46) pxd(46) other(1050)
| Conf files: dockerfile(1) devcontainer.json(1) github-actions(1)
| Launch Configs: debugpy(3);
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nes-gb3-4k:31552341
Type: Performance Issue
Behaviour
pytest runner in the left panel seems to do something like dist=load despite my settings.json, resulting in periodic bottlenecking on slow tests.
Steps to reproduce:
Running my large suite with
uv run pytest tests -n auto --dist workstealsaturates CPU and gives long ..... lines undifferentiated by filenames. But execting the runner with settings.json{ "python.testing.pytestArgs": [ "tests", "-n", "auto", "--dist", "worksteal" ], "python.testing.unittestEnabled": false, "python.testing.pytestEnabled": true }produces a long list of FILENAME ..... [PCT%] lines, and repeated bursts of full core saturation interspersed by long stretches of single-core usage in a single suite run.
Diagnostic data
Details
Excerpt from the TEST RESULTS panel:
vs a (non-vscode) terminal run
Extension version: 2026.4.0
VS Code version: Code 1.129.1 (8a7abeba6e03ea3af87bfbce9a1b7e48fed567b8, 2026-07-17T15:35:09Z)
OS version: Windows_NT x64 10.0.26200
Modes:
Remote OS version: Linux x64 6.14.0-37-generic
python.languageServersetting: DefaultUser Settings
Installed Extensions
System Info
GPU0: VENDOR= 0x1002, DEVICE=0x15e7 [AMD Radeon (TM) Graphics], DRIVER_VENDOR=AMD, DRIVER_VERSION=31.0.21923.13006 ACTIVE
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8875
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off
Process Info
Workspace Info
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