How do I launch multiple runs from one script?

Support:

  less than a minute  

Finish previous runs before starting new runs to log multiple runs within a single script.

The recommended way to do this is by using wandb.init() as a context manager because this finishes the run and marks it as failed if your script raises an exception:

import wandb

for x in range(10):
    with wandb.init() as run:
        for y in range(100):
            run.log({"metric": x + y})

You can also call run.finish() explicitly:

import wandb

for x in range(10):
    run = wandb.init()

    try:
        for y in range(100):
            run.log({"metric": x + y})

    except Exception:
        run.finish(exit_code=1)
        raise

    finally:
        run.finish()

Multiple active runs

Starting with wandb 0.19.10, you can set the reinit setting to "create_new" to create multiple simultaneously active runs.

import wandb

with wandb.init(reinit="create_new") as tracking_run:
    for x in range(10):
        with wandb.init(reinit="create_new") as run:
            for y in range(100):
                run.log({"x_plus_y": x + y})

            tracking_run.log({"x": x})

See Multiple runs per process for more information about reinit="create_new", including caveats about W&B integrations.


Last modified September 3, 2025