FThreads

This repo is a playground for testing out Python's new free-threading features in versions 3.13 and 3.14. I wanted to see firsthand how things change now that we’re moving away from the Global Interpreter Lock (GIL).

To put it to the test, I built a MapReduce setup that uses multiple workers for parallel processing. It's pretty cool because modern packages can now actually turn off the GIL, as long as they have extension modules that handle preemptive scheduling safely.

I also got a lot of inspiration from Tiago Rodrigues Antão’s book, Fast Python (2023). He does a deep dive into concurrency using asyncio and multiprocessing in Chapter 3, but since the book came out before these latest Python updates, I decided to do a fresh exploration using the python3.13t build.

sequenceDiagram
    actor Client
    participant Server
    participant WQ as Worker Queue
    participant Worker as Worker Thread<br/>(Isolated Thread)
    participant RQ as Result Queue

    Client->>Server: request (MR)
    activate Server
    Server->>WQ: job params
    Server-->>Client: returns Job id
    deactivate Server

    Note over Worker: No GIL
    Worker->>WQ: pick
    activate Worker
    Worker->>Worker: execute
    Worker->>RQ: publish result
    deactivate Worker

    Client->>RQ: pick up result
    RQ-->>Client: result

Loading

Setup

1. Install uv if not already installed in your machine.
2. Setup dev environment using python3.13t.

uv sync --dev

Tests

• Run the server using the following command:

export PYTHON_GIL=0
uv run python -t server.py

• Run the load test in a different console with the desired parameters:

# uv run python test_load.py {num_requests} --chunk-size {down_chunk_size} {up_chunk_size}
uv run python test_load.py 3 --chunk-size 1000 2000

The num_requests indicate the number of client requests to the server.

The down_chunk_size and up_chunk_size are the bound limits for the corpus length.

Additional Commands

• Typecheck run

make typecheck

• Unit tests run

make test

Author

• Mario Reyes Ojeda