journal_storage_warning.py

import optuna

from concurrent.futures import ProcessPoolExecutor, as_completed
from optuna.storages import JournalStorage
from optuna.storages.journal import JournalFileBackend

optuna.logging.set_verbosity(optuna.logging.WARNING)
n_processes = 8
study_name = "foo"
filename = "optuna-journal.log"


def objective(trial: optuna.Trial) -> float:
    s = 0.0
    for i in range(18):
        trial.set_user_attr(f"attr{i}", "attr value")
    for i in range(8):
        s += trial.suggest_float(f"x{i}", -10, 10) ** 2
    return s


def optimize(n_trials: int):
    storage = JournalStorage(JournalFileBackend(filename))
    study = optuna.create_study(
        storage=storage,
        study_name=study_name,
        sampler=optuna.samplers.RandomSampler(),
        load_if_exists=True
    )
    study.optimize(objective, n_trials=n_trials)


def main():
    futures = []
    with ProcessPoolExecutor(max_workers=n_processes) as pool:
        for i in range(n_processes):
            futures.append(pool.submit(optimize, 100))
        
        for future in as_completed(futures):
            future.result()


if __name__ == "__main__":
    main()