Profiling

Profiling the Extension

If you find yourself with the need to profile the extension, here's some steps you can take to get a usable profile:

1. npm install -g vsce <- This is the vscode extension packager. It needs to be global
2. npm run package <- This will generate a vsix of your development bits
3. Close VS code
4. Navigate to your user/.vscode/extensions directory
5. Delete all ms-python directories there.
6. Open VS Code and run the 'Install From VSIX' command to install the vsix you just generated.

This gets your bits (and only your bits) installed as a package inside of VS Code without having to run the debugger.

Debug Bits

The next step is to make those bits non-minified.

1. npm run clean <- This will clean your output directory
2. npm run compile
3. npm run compile-webviews
4. Copy the 'out' directory from your source code overtop of the 'out' directory in your user/.vscode/extensions/ms-python directory
5. Copy the 'node_modules' directory from your source next to the 'out' directory in your user/.vscode/extensions/ms-python directory. This might take a while.

Now you have debug bits installed.

Running the profiler

Follow the directions here: https://github.com/Microsoft/vscode/wiki/Performance-Issues#profile-the-running-extensions

You should generate a profile and save it. You can then load it into any Chrome javscript profiler and look at the results.

I found using the 'Chart' view and searching (CTRL+F) for classes/functions I thought might be expensive was a good way to start:

Profiling tests

Based on the instructions here, you can also use chrome to profile the mocha tests: https://medium.com/@paul_irish/debugging-node-js-nightlies-with-chrome-devtools-7c4a1b95ae27

Essentially I did this:

1. Open chrome://inspect in chrome
2. Run node .\node_modules\mocha\bin\mocha --inspect-brk --require source-map-support/register --opts ./build/.mocha.functional.opts "--grep=Simple text"
3. In the chrome inspector, wait for the node process to show up
4. Click the 'Open Dedicated DevTools for Node'
5. Debug breakpoint on entry should hit
6. Switch to profiler and start profiling
7. Once done the profile can be inspected in that window or saved and opened in another chrome window.