Parallel error with GridSearchCV, works fine with other methods

Question

I am encounteringt the following problems using GridSearchCV: it gives me a parallel error while using n_jobs > 1. At the same time n_jobs > 1 wo

Answer 1

I think you are using windows. You need to wrap the grid search in a function and then call inside __name__ == '__main__'. Joblib parallel n_jobs=-1 determines the number of jobs to use which in parallel doesn't work on windows all the time.

Try wrapping grid search in a function:

def somefunction():
    clf = ensemble.RandomForestClassifier()
    param_grid = {'n_estimators': [10,20]}
    grid_s= model_selection.GridSearchCV(clf,   param_grid=param_grid_gb,n_jobs=-1,verbose=1)
    grid_s.fit(train, targ)
    return grid_s

if __name__ == '__main__':
    somefunction()

Or:

if __name__ == '__main__':
    clf = ensemble.RandomForestClassifier()
    param_grid = {'n_estimators': [10,20]}
    grid_s= model_selection.GridSearchCV(clf,   param_grid=param_grid_gb,n_jobs=-1,verbose=1)
    grid_s.fit(train, targ)