[tune] Fix numerical error (#5653)

python/ray/tune/resources.py

@@ -5,11 +5,10 @@ from __future__ import print_function
 from collections import namedtuple
 import logging
 import json
+from numbers import Number
 # For compatibility under py2 to consider unicode as str
 from six import string_types
 
-from numbers import Number
-
 from ray.tune import TuneError
 
 logger = logging.getLogger(__name__)
@@ -66,6 +65,23 @@ class Resources(
             custom_resources.setdefault(value, 0)
             extra_custom_resources.setdefault(value, 0)
 
+        cpu = round(cpu, 2)
+        gpu = round(gpu, 2)
+        memory = round(memory, 2)
+        object_store_memory = round(object_store_memory, 2)
+        extra_cpu = round(extra_cpu, 2)
+        extra_gpu = round(extra_gpu, 2)
+        extra_memory = round(extra_memory, 2)
+        extra_object_store_memory = round(extra_object_store_memory, 2)
+        custom_resources = {
+            resource: round(value, 2)
+            for resource, value in custom_resources.items()
+        }
+        extra_custom_resources = {
+            resource: round(value, 2)
+            for resource, value in extra_custom_resources.items()
+        }
+
         all_values = [
             cpu, gpu, memory, object_store_memory, extra_cpu, extra_gpu,
             extra_memory, extra_object_store_memory

python/ray/tune/tests/test_trial_runner.py

@@ -1531,6 +1531,14 @@ class TrialRunnerTest(unittest.TestCase):
         self.assertEqual(trials[2].status, Trial.PENDING)
         self.assertEqual(trials[3].status, Trial.PENDING)
 
+    def testResourceNumericalError(self):
+        resource = Resources(cpu=0.99, gpu=0.99, custom_resources={"a": 0.99})
+        small_resource = Resources(
+            cpu=0.33, gpu=0.33, custom_resources={"a": 0.33})
+        for i in range(3):
+            resource = Resources.subtract(resource, small_resource)
+        self.assertTrue(resource.is_nonnegative())
+
     def testResourceScheduler(self):
         ray.init(num_cpus=4, num_gpus=1)
         runner = TrialRunner()