fix for n_jobs=-1, resolves #692 (#733)

* fix for n_jobs=-1

* using joblib.cpu_count() instead of custom function

* trying to appease flake8

* PEP8

Co-authored-by: Matthias Feurer <[email protected]>

Author: Ashafix

autosklearn/estimators.py

@@ -6,6 +6,7 @@
 import numpy as np
 from sklearn.base import BaseEstimator
 from sklearn.utils.multiclass import type_of_target
+import joblib
 
 from autosklearn.automl import AutoMLClassifier, AutoMLRegressor, BaseAutoML
 from autosklearn.util.backend import create, get_randomized_directory_names
@@ -341,7 +342,11 @@ def fit(self, **kwargs):
                 output_directory=self.output_folder,
             )
 
-            self._n_jobs = self.n_jobs
+            if self.n_jobs == -1:
+                self._n_jobs = joblib.cpu_count()
+            else:
+                self._n_jobs = self.n_jobs
+
             shared_mode = True
             seeds = set()
             for i in range(self._n_jobs):
@@ -508,7 +513,6 @@ def refit(self, X, y):
         self._automl[0].refit(X, y)
         return self
 
-
     def predict(self, X, batch_size=None, n_jobs=1):
         return self._automl[0].predict(X, batch_size=batch_size, n_jobs=n_jobs)
 

test/test_automl/test_estimators.py

@@ -9,17 +9,20 @@
 import numpy as np
 import numpy.ma as npma
 
+from joblib import cpu_count
+
 import autosklearn.pipeline.util as putil
+import autosklearn.estimators  # noqa F401
 from autosklearn.estimators import AutoSklearnEstimator
 from autosklearn.classification import AutoSklearnClassifier
 from autosklearn.regression import AutoSklearnRegressor
 from autosklearn.metrics import accuracy, f1_macro, mean_squared_error
 from autosklearn.automl import AutoMLClassifier, AutoML
 from autosklearn.util.backend import Backend, BackendContext
 from autosklearn.constants import BINARY_CLASSIFICATION
-sys.path.append(os.path.dirname(__file__))
 from base import Base
 
+sys.path.append(os.path.dirname(__file__))
 
 class ArrayReturningDummyPredictor(object):
     def __init__(self, test):
@@ -479,6 +482,17 @@ def test_fit_n_jobs_2(self):
 
         self.assertEqual(len(seeds), 1)
 
+    @unittest.mock.patch('autosklearn.estimators.AutoSklearnEstimator.build_automl')
+    def test_fit_n_jobs_negative(self, build_automl_patch):
+        n_cores = cpu_count()
+        cls = AutoSklearnEstimator(n_jobs=-1)
+        cls.fit()
+        self.assertEqual(len(cls._automl), n_cores)
+
+    def test_get_number_of_available_cores(self):
+        n_cores = cpu_count()
+        self.assertGreaterEqual(n_cores, 1)
+
 
 class AutoMLClassifierTest(Base, unittest.TestCase):
     @unittest.mock.patch('autosklearn.automl.AutoML.predict')