[Deploy] Refine Autoscaling Algorithm

python/fedml/computing/scheduler/comm_utils/job_monitor.py

@@ -28,7 +28,8 @@
 from .job_utils import JobRunnerUtils
 from ..model_scheduler.device_http_proxy_inference_protocol import FedMLHttpProxyInference
 from ..model_scheduler.device_model_cache import FedMLModelCache
-from ..model_scheduler.autoscaler.autoscaler import Autoscaler, EWMPolicy, ConcurrentQueryPolicy
+from ..model_scheduler.autoscaler.autoscaler import Autoscaler
+from ..model_scheduler.autoscaler.policies import ConcurrentQueryPolicy
 from ..model_scheduler.device_model_db import FedMLModelDatabase
 from ..model_scheduler.device_mqtt_inference_protocol import FedMLMqttInference
 from ..slave import client_constants
@@ -109,8 +110,14 @@ def autoscaler_reconcile_after_interval(self):
                 # Set the policy, here we use latency, but other metrics are possible as well, such as qps.
                 # For more advanced use cases look for the testing scripts under the autoscaler/test directory.
                 autoscaling_policy_config = \
-                    {"queries_per_replica": endpoint_settings["target_queries_per_replica"],
-                     "window_size_secs": endpoint_settings["aggregation_window_size_seconds"]}
+                    {
+                        "current_replicas": int(endpoint_settings["replica_num"]),
+                        "min_replicas": int(endpoint_settings["scale_min"]),
+                        "max_replicas": int(endpoint_settings["scale_max"]),
+                        "queries_per_replica": int(endpoint_settings["target_queries_per_replica"]),
+                        "window_size_secs": int(endpoint_settings["aggregation_window_size_seconds"]),
+                        "scaledown_delay_secs": int(endpoint_settings["scale_down_delay_seconds"]),
+                    }
                 autoscaling_policy = ConcurrentQueryPolicy(**autoscaling_policy_config)
 
                 e_id, e_name, model_name = endpoint_settings["endpoint_id"], endpoint_settings["endpoint_name"], \

python/fedml/computing/scheduler/model_scheduler/autoscaler/policies.py

@@ -0,0 +1,98 @@
+from pydantic import BaseModel, field_validator, NonNegativeInt, NonNegativeFloat
+
+
+class AutoscalingPolicy(BaseModel):
+    """
+    Below are some default values for every endpoint.
+
+    The following parameters refer to:
+    - current_replicas: the number of currently running replicas of the endpoint
+    - min_replicas: the minimum number of replicas of the endpoint in the instance group
+    - max_replicas: the maximum number of replicas of the endpoint in the instance group
+    - release_replica_after_idle_secs: when to release a single idle replica
+    - scaledown_delay_secs: how many seconds to wait before performing a scale down operation
+    - scaleup_cost_secs: how many seconds it takes/costs to perform a scale up operation
+    - previous_triggering_value: the last value that triggered a scaling operation
+
+    The `replica_idle_grace_secs` parameter is used as
+    the monitoring interval after which a running replica
+    of an idle endpoint should be released.
+    """
+    current_replicas: NonNegativeInt
+    min_replicas: NonNegativeInt
+    max_replicas: NonNegativeInt
+    previous_triggering_value: float = None
+    release_replica_after_idle_secs: NonNegativeInt = 300  # default is after 5 minutes
+    scaledown_delay_secs: NonNegativeInt = 60  # default is 1 minute
+    scaleup_cost_secs: NonNegativeInt = 300  # default is 5 minutes
+
+
+class EWMPolicy(AutoscalingPolicy):
+    """
+    Configuration parameters for the reactive autoscaling policy.
+    EWM stands for Exponential Weighted Calculations, since we use
+    the pandas.DataFrame.ewm() functionality.
+
+    For panda's EWM using alpha = 0.1, we indicate that the most recent
+    values are weighted more. The reason is that the exponential weighted
+    mean formula in pandas is computed as:
+        Yt = X_t + (1-a) * X_{t-1} + (1-a)^2 X_{t-2} / (1 + (1-a) + (1-a)^2)
+
+    The following parameters refer to:
+    - ewm_mins: the length of the interval we consider for reactive decision
+    - ewm_alpha: the decay factor for the exponential weighted interval
+    - ewm_latest: the latest recorded value of the metric's exponential weighted mean
+    - ub_threshold: the upper bound scaling factor threshold for reactive decision
+    - lb_threshold: the lower bound scaling factor threshold for reactive decision
+
+    Example:
+
+        Let's say that we consider 15 minutes as the length of our interval and a
+        decay factor alpha with a value of 0.5:
+            Original Sequence: [0.1, 0.2, 0.4, 3, 5, 10]
+            EWM Sequence: [0.1, [0.166, 0.3, 1.74, 3.422, 6.763]
+
+        If we assume that our previous scaling operation was triggered at value Y,
+        then the conditions we use to decide whether to scale up or down are:
+            Latency:
+                ScaleUP: X > ((1 + ub_threshold) * Y)
+                ScaleDown: X < (lb_threshold * Y)
+            QPS:
+                ScaleUP: X < (lb_threshold * Y)
+                ScaleDown: X < ((1 + ub_threshold) * Y)
+
+        In other words, QPS is the inverse of Latency and vice versa.
+    """
+    metric: str  # possible values: ["ewm_latency", "ewm_qps"]
+    ewm_mins: NonNegativeInt  # recommended value: 15 minutes
+    ewm_alpha: NonNegativeFloat  # recommended value: 0.1
+    ewm_latest: NonNegativeFloat = None  # will be filled by the algorithm
+    ub_threshold: NonNegativeFloat  # recommended value: 0.5
+    lb_threshold: NonNegativeFloat  # recommended value: 0.5
+
+    @field_validator("metric")
+    def validate_option(cls, v):
+        assert v in ["ewm_latency", "ewm_qps"]
+        return v
+
+
+class ConcurrentQueryPolicy(AutoscalingPolicy):
+    """
+    This policy captures the number of queries we want to support
+    per replica over the defined window length in seconds.
+    """
+    queries_per_replica: NonNegativeInt  # recommended is at least 1 query
+    window_size_secs: NonNegativeInt  # recommended is at least 60seconds
+
+
+class MeetTrafficDemandPolicy(AutoscalingPolicy):
+    """
+    This policy captures the number of queries we want to support
+    per replica over the defined window length in seconds.
+    """
+    window_size_secs: NonNegativeInt
+
+
+class PredictivePolicy(AutoscalingPolicy):
+    # TODO(fedml-dimitris): TO BE COMPLETED!
+    pass

python/fedml/computing/scheduler/model_scheduler/autoscaler/test/autoscaler_test.py

@@ -3,19 +3,33 @@
 import time
 
 from collections import namedtuple
-from fedml.computing.scheduler.model_scheduler.autoscaler.autoscaler import Autoscaler, EWMPolicy, ConcurrentQueryPolicy
+from fedml.computing.scheduler.model_scheduler.autoscaler.policies import *
+from fedml.computing.scheduler.model_scheduler.autoscaler.autoscaler import Autoscaler, ScaleOp
 from fedml.computing.scheduler.model_scheduler.device_model_cache import FedMLModelCache
 from fedml.core.mlops.mlops_runtime_log import MLOpsRuntimeLog
 
 ENV_REDIS_ADDR = "local"
 ENV_REDIS_PORT = 6379
 ENV_REDIS_PASSWD = "fedml_default"
 ENV_ENDPOINT_ID_1 = 12345
-ENV_ENDPOINT_ID_2 = 77777
 
 
 class AutoscalerTest(unittest.TestCase):
 
+    @classmethod
+    def populate_redis_with_dummy_metrics(cls):
+        fedml_model_cache = FedMLModelCache.get_instance()
+        fedml_model_cache.set_redis_params(ENV_REDIS_ADDR, ENV_REDIS_PORT, ENV_REDIS_PASSWD)
+        fedml_model_cache.set_monitor_metrics(
+            ENV_ENDPOINT_ID_1, "", "", "", 5, 5, 5, 10, 100, 100, int(time.time_ns() / 1000), 0)
+
+    @classmethod
+    def clear_redis(cls):
+        fedml_model_cache = FedMLModelCache.get_instance()
+        # Clean up redis after test.
+        fedml_model_cache.delete_endpoint_metrics(
+            endpoint_ids=[ENV_ENDPOINT_ID_1])
+
     def test_autoscaler_singleton_pattern(self):
         autoscaler_1 = Autoscaler.get_instance()
         autoscaler_2 = Autoscaler.get_instance()
@@ -24,72 +38,118 @@ def test_autoscaler_singleton_pattern(self):
         self.assertTrue(autoscaler_1 is autoscaler_2)
 
     def test_scale_operation_single_endpoint_ewm_policy(self):
-
-        # Populate redis with some dummy values for each endpoint before running the test.
-        fedml_model_cache = FedMLModelCache.get_instance()
-        fedml_model_cache.set_redis_params(ENV_REDIS_ADDR, ENV_REDIS_PORT, ENV_REDIS_PASSWD)
-        fedml_model_cache.set_monitor_metrics(
-            ENV_ENDPOINT_ID_1, "", "", "", 5, 5, 5, 10, 100, 100, int(time.time_ns() / 1000), 0)
-        fedml_model_cache.set_monitor_metrics(
-            ENV_ENDPOINT_ID_1, "", "", "", 5, 5, 5, 10, 100, 100, int(time.time_ns() / 1000), 0)
-
+        self.populate_redis_with_dummy_metrics()
         # Create autoscaler instance and define policy.
         autoscaler = Autoscaler.get_instance()
         latency_reactive_policy_default = {
+            "current_replicas": 1,
             "min_replicas": 1,
             "max_replicas": 1,
-            "current_replicas": 1,
             "metric": "ewm_latency",
             "ewm_mins": 15,
             "ewm_alpha": 0.5,
             "ub_threshold": 0.5,
             "lb_threshold": 0.5
         }
-
         autoscaling_policy = EWMPolicy(**latency_reactive_policy_default)
         scale_op_1 = autoscaler.scale_operation_endpoint(
             autoscaling_policy,
             endpoint_id=ENV_ENDPOINT_ID_1)
-        scale_op_2 = autoscaler.scale_operation_endpoint(
-            autoscaling_policy,
-            endpoint_id=ENV_ENDPOINT_ID_2)
-
-        # Clean up redis after test.
-        fedml_model_cache.delete_model_endpoint_metrics(
-            endpoint_ids=[ENV_ENDPOINT_ID_1, ENV_ENDPOINT_ID_2])
 
         # TODO Change to ScaleUP or ScaleDown not only not None.
         self.assertIsNotNone(scale_op_1)
-        self.assertIsNotNone(scale_op_2)
+        self.clear_redis()
 
     def test_scale_operation_single_endpoint_concurrency_query_policy(self):
+        self.populate_redis_with_dummy_metrics()
+        # Create autoscaler instance and define policy.
+        autoscaler = Autoscaler.get_instance()
+        concurrent_query_policy = {
+            "current_replicas": 1,
+            "min_replicas": 1,
+            "max_replicas": 1,
+            "queries_per_replica": 1,
+            "window_size_secs": 60
+        }
+        autoscaling_policy = ConcurrentQueryPolicy(**concurrent_query_policy)
+        scale_op_1 = autoscaler.scale_operation_endpoint(
+            autoscaling_policy,
+            endpoint_id=ENV_ENDPOINT_ID_1)
 
-        # Populate redis with some dummy values for each endpoint before running the test.
-        fedml_model_cache = FedMLModelCache.get_instance()
-        fedml_model_cache.set_redis_params(ENV_REDIS_ADDR, ENV_REDIS_PORT, ENV_REDIS_PASSWD)
-        fedml_model_cache.set_monitor_metrics(
-            ENV_ENDPOINT_ID_1, "", "", "", 5, 5, 5, 10, 100, 100, int(time.time_ns() / 1000), 0)
+        # TODO Change to ScaleUP or ScaleDown not only not None.
+        self.assertIsNotNone(scale_op_1)
+        self.clear_redis()
 
+    def test_scale_operation_single_endpoint_meet_traffic_demand_query_policy(self):
+        self.populate_redis_with_dummy_metrics()
         # Create autoscaler instance and define policy.
         autoscaler = Autoscaler.get_instance()
         concurrent_query_policy = {
+            "current_replicas": 1,
             "min_replicas": 1,
             "max_replicas": 1,
-            "current_replicas": 1,
-            "queries_per_replica": 2, "window_size_secs": 60
+            "window_size_secs": 60
         }
-
-        autoscaling_policy = EWMPolicy(**concurrent_query_policy)
+        autoscaling_policy = MeetTrafficDemandPolicy(**concurrent_query_policy)
         scale_op_1 = autoscaler.scale_operation_endpoint(
             autoscaling_policy,
             endpoint_id=ENV_ENDPOINT_ID_1)
 
-        # Clean up redis after test.
-        fedml_model_cache.delete_model_endpoint_metrics(
-            endpoint_ids=[ENV_ENDPOINT_ID_1])
-
         # TODO Change to ScaleUP or ScaleDown not only not None.
         self.assertIsNotNone(scale_op_1)
+        self.clear_redis()
+
+    def test_validate_scaling_bounds(self):
+        # Create autoscaler instance and define policy.
+        autoscaler = Autoscaler.get_instance()
+        autoscaling_policy = {
+            "current_replicas": 2,
+            "min_replicas": 1,
+            "max_replicas": 3,
+        }
+        autoscaling_policy = AutoscalingPolicy(**autoscaling_policy)
+
+        # Validate scale up.
+        scale_up = autoscaler.validate_scaling_bounds(ScaleOp.UP_OUT_OP, autoscaling_policy)
+        self.assertEquals(scale_up, ScaleOp.UP_OUT_OP)
+
+        # Validate scale down.
+        scale_down = autoscaler.validate_scaling_bounds(ScaleOp.DOWN_IN_OP, autoscaling_policy)
+        self.assertEquals(scale_down, ScaleOp.DOWN_IN_OP)
+
+        # Validate max out-of-bounds.
+        autoscaling_policy.current_replicas = 3
+        scale_oob_max = autoscaler.validate_scaling_bounds(ScaleOp.UP_OUT_OP, autoscaling_policy)
+        self.assertEquals(scale_oob_max, ScaleOp.NO_OP)
+
+        # Validate min out-of-bounds.
+        autoscaling_policy.current_replicas = 1
+        scale_oob_min = autoscaler.validate_scaling_bounds(ScaleOp.DOWN_IN_OP, autoscaling_policy)
+        self.assertEquals(scale_oob_min, ScaleOp.NO_OP)
+
+    def test_enforce_scaling_down_delay_interval(self):
+        self.populate_redis_with_dummy_metrics()
+        # Create autoscaler instance and define policy.
+        autoscaler = Autoscaler.get_instance()
+        autoscaling_policy = {
+            "current_replicas": 1,
+            "min_replicas": 1,
+            "max_replicas": 1,
+        }
+        autoscaling_policy = AutoscalingPolicy(**autoscaling_policy)
+
+        autoscaling_policy.scaledown_delay_secs = 0.0
+        scale_down = autoscaler.enforce_scaling_down_delay_interval(ENV_ENDPOINT_ID_1, autoscaling_policy)
+        self.assertEquals(scale_down, ScaleOp.DOWN_IN_OP)
+
+        autoscaling_policy.scaledown_delay_secs = 1
+        scale_noop = autoscaler.enforce_scaling_down_delay_interval(ENV_ENDPOINT_ID_1, autoscaling_policy)
+        self.assertEquals(scale_noop, ScaleOp.NO_OP)
+
+        time.sleep(2)
+        scale_down = autoscaler.enforce_scaling_down_delay_interval(ENV_ENDPOINT_ID_1, autoscaling_policy)
+        self.assertEquals(scale_down, ScaleOp.DOWN_IN_OP)
+        self.clear_redis()
 
 
 if __name__ == "__main__":