This PR adds--jsonl discussed in#146256.

It's a draft - it does not contain tests yet. The class is below 2**8 lines of code and does not touch existingprofiling.sampling code, so I took a leap. I'm already uncomfortable with creating a PR for an issue that wasn't widely discussed. I don't want to clutter it with tests, until the format is solidified.

For example:

sudo -E \  uv run \    --python /Users/maurycy/src/github.com/maurycy/cpython/python.exe \      python \        -m profiling.sampling \           run \             --jsonl \             -o /tmp/profile.jsonl /tmp/hello_world.py

Where/tmp/hello_world.py could be:

importtimeprint("Hello, World!")time.sleep(0.1)

Given the similarity, the class just inherits fromStackTraceCollector. (I think this is a good hint that the collectors should be separate from renderers.)

Visual Studio Code Extension

For the purpose of demonstrating the--jsonl usefulness,I have vibe-coded (with Claude Code) a simple VSCode Extension that leverages this play profile and displays it in the editor:

I think that, once we have--stream it will be much more exciting.

Apart from headless profilers:updating the real-time hot spots from the production in VSCode, or, well, making agents' life easier.

You can fetch the vibe-coded VSCode Extension here (no guarantees):

• https://gist.github.com/maurycy/50a80586636a90216efc86065bbfd6de
• https://gist.github.com/maurycy/fa4c3acd9e8e681a609bddc9ad04c4ae

Or:

mkdir -p~/.vscode/extensions/profiling-heatmap                                                                                                                                                                                   curl -sL'https://gist.githubusercontent.com/maurycy/50a80586636a90216efc86065bbfd6de/raw/719e46f4f086c819edbbee7b20c45c41eae15e8b/extension.js' -o~/.vscode/extensions/profiling-heatmap/extension.js                           curl -sL'https://gist.githubusercontent.com/maurycy/fa4c3acd9e8e681a609bddc9ad04c4ae/raw/1edd3c2716a4a9e55aba8ed94850fd70f61fa606/package.json' -o~/.vscode/extensions/profiling-heatmap/package.jsonecho"Restart VSCode, then: Cmd+Shift+P -> 'Profiling: Load JSONL Profile'"

Please do not forget about removing~/.vscode/extensions/profiling-heatmap/ after tests.

• Issue:Add--jsonl flag to theprofiling.sampling #146256