BruteForceSampler stops before suggesting all combinations in parallel optimization #5780
Description
Expected behavior
BruteForceSampler should suggest all parameter combinations, but it stops unexpectedly before that in parallel optimization.
Environment
- Optuna version:4.2.0.dev
- Python version:3.9.4
- OS:macOS-15.1-x86_64-i386-64bit
- (Optional) Other libraries and their versions:
Error messages, stack traces, or logs
See the following MRE.Steps to reproduce
import time
import optuna
def objective(trial):
x = trial.suggest_int("x", 0, 1)
time.sleep(x)
y = trial.suggest_int("y", 0, 1)
return x + y
sampler = optuna.samplers.BruteForceSampler(seed=42)
study = optuna.create_study(sampler=sampler)
study.optimize(objective, n_jobs=2)[I 2024-11-22 17:43:20,854] A new study created in memory with name: no-name-86ca63d9-e334-4237-a5a5-854dd2483f9f
[I 2024-11-22 17:43:20,855] Trial 0 finished with value: 1.0 and parameters: {'x': 0, 'y': 1}. Best is trial 0 with value: 1.0.
[I 2024-11-22 17:43:20,856] Trial 2 finished with value: 0.0 and parameters: {'x': 0, 'y': 0}. Best is trial 2 with value: 0.0.
[I 2024-11-22 17:43:21,861] Trial 1 finished with value: 1.0 and parameters: {'x': 1, 'y': 0}. Best is trial 2 with value: 0.0.
Additional context (optional)
No response