Configure XGBoost "n_jobs" Parameter

The n_jobs parameter in XGBoost controls the number of parallel threads used for training, which can significantly speed up the training process on multi-core machines.

The n_jobs parameter determines the number of CPU cores used for parallel processing during the training of an XGBoost model.

from sklearn.datasets import make_classification
from sklearn.model_selection import train_test_split
from xgboost import XGBClassifier

# Generate synthetic data
X, y = make_classification(n_samples=100000, n_features=20, n_informative=10, n_redundant=5, random_state=42)

# Split the dataset into training and test sets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)

# Initialize the XGBoost classifier with a specific n_jobs value
model = XGBClassifier(n_jobs=4, eval_metric='logloss')

# Fit the model
model.fit(X_train, y_train)

The n_jobs parameter is an alias for the (deprecated) nthread parameter in the XGBoost API.

You can learn more about the nthread parameter in the examples:

• Configure XGBoost “nthread” Parameter
• XGBoost Compare “n_jobs” vs “nthread” Parameters

The n_jobs parameter accepts integer values, with -1 indicating that all available cores should be used.

• The default value of n_jobs in XGBoost is set to the number of logical CPU cores in the system.

It’s important to note that n_jobs only affects the training speed and has no impact on the model’s performance.

Choosing the Right “n_jobs” Value

When setting the n_jobs parameter, there is a trade-off between training speed and resource consumption:

• Higher values can significantly reduce training time but may monopolize system resources, potentially slowing down or freezing other applications.
• Lower values (or 1) can be used to limit resource usage, but this comes at the cost of slower training.

Consider the following guidelines when choosing the n_jobs value:

• For dedicated machines or when fast training is a priority, set n_jobs to -1 to use all available cores.
• For shared systems or limited resources, set n_jobs to a lower value (e.g., half of the available cores) to balance training speed and resource usage.
• Setting n_jobs to 1 effectively disables parallelization and may be suitable for low-priority tasks or when resources are scarce.

You can learn more about configuring the n_jobs parameter in the example:

• Tune XGBoost “n_jobs” Parameter
• XGBoost Configure “n_jobs” for Grid Search
• XGBoost Configure “n_jobs” for Random Search

Practical Tips

• Experiment with different n_jobs values to find the optimal balance between training speed and resource usage for your specific setup.
• Be cautious when using all available cores (n_jobs=-1), as it may slow down or freeze other applications during training.
• Monitor system resources (CPU usage, memory) while training with different n_jobs values to ensure the machine remains responsive.