feat/58 - improve Backpressure algorithm

amqp/adapter/backpressure_handler.py

@@ -3,6 +3,7 @@ import json
 import time
 from asyncio import AbstractEventLoop
 from threading import Thread
+from typing import Optional
 
 import psutil
 from aio_pika import Message
@@ -94,9 +95,8 @@ class RunningAverage:
 
 class BackpressureHandler:
     # Track the number of messages currently being processed
-    current_parallel_executions = 0
+    current_load = 0
     # helps detect IDLE condition
-    last_data_message_time = 0
     # helps prevent flooding the system with backpressure events
     last_backpressure_event_time = 0
     last_backpressure_event = ScalingRequestAlert.UPDATE
@@ -116,50 +116,38 @@ class BackpressureHandler:
         self.exchange = None
         self.swarm_service_id = self.config.amq_adapter.swarm_service_id
         self.swarm_task_id = self.config.amq_adapter.swarm_task_id
-        self.parallel_workers = self.config.backpressure.threshold_threads
+        self.maximum_load = self.config.backpressure.threshold_load
         self.average_cpu_usage = None
         self.do_loop = -1
-        self._resource_usage_state = RESOURCE_UNSET
         self._resource_usage_changed = 0
         self._resource_average_value = 0
         self._last_resource_max_value = 100  # Default max value for CPU usage
 
-    def _do_loop(self) -> bool:
-        """
-        Check if the loop should continue running.
-        Positive value of do_loop indicates the number of iterations left.
-        Negative value indicates the loop should run indefinitely.
-        """
-        _val = self.do_loop != 0
-        if self.do_loop > 0:
-            self.do_loop -= 1
-        return _val
-
-    def increase_parallel_executions(self):
-        """Increase the number of parallel executions"""
+    def increase_current_load(self):
+        """Increase the number of parallel executions, or current load"""
         logging_info(
             "Backpressure: Increase parallel executions, current=%s",
-            self.current_parallel_executions,
+            self.current_load,
         )
-        self.current_parallel_executions += 1
+        self.current_load += 1
 
-    def decrease_parallel_executions(self):
-        """Decrease the number of parallel executions"""
+    def decrease_current_load(self):
+        """Decrease the number of parallel executions, or current load"""
         logging_info(
             "Backpressure: Decrease parallel executions, current=%s",
-            self.current_parallel_executions,
+            self.current_load,
         )
-        if self.current_parallel_executions > 0:
-            self.current_parallel_executions -= 1
+        if self.current_load > 0:
+            self.current_load -= 1
 
-    def update_parallel_executions(self, count: int):
-        """Update the number of parallel executions"""
-        self.current_parallel_executions = count
+    def update_current_load(self, count: int):
+        """Update the number of parallel executions, or current load"""
+        self.current_load = count
 
     def update_last_data_message_time(self):
-        logging_info("Backpressure: Update last data message time")
+        # logging_info("Backpressure: Update last data message time")
         """Update the last data message time"""
-        self.last_data_message_time = time.time()
+        self.last_backpressure_event_time = time.time()
 
     async def update_backpressure_value(self, current: int, maximum: int):
         """
@@ -172,37 +160,30 @@ class BackpressureHandler:
             maximum: Maximum value of the backpressure metric
         """
         logging_info(
-            "Backpressure: Updating backpressure value, current=%s, maximum=%s",
-            current,
-            maximum
+            "Backpressure: Updating backpressure value, current=%s, maximum=%s", current, maximum
         )
+        if maximum > 0 and maximum > self.maximum_load:
+            self.maximum_load = maximum
 
         # Update the current parallel executions count
-        self.update_parallel_executions(current)
-        
-        # Update the last data message time to indicate activity
-        self.update_last_data_message_time()
+        self.update_current_load(current)
 
         # Check for overload conditions
         await self.check_overload_condition()
 
+        # Update the last data message time to indicate activity
+        self.update_last_data_message_time()
+
         # If maximum has changed, update the parallel workers threshold
-        if maximum != self.parallel_workers and maximum > 0:
+        if maximum != self.maximum_load and maximum > 0:
             logging_info(
                 "Backpressure: Updating maximum parallel workers from %s to %s",
-                self.parallel_workers,
-                maximum
+                self.maximum_load,
+                maximum,
             )
-            self.parallel_workers = maximum
-
-    def start_backpressure_monitor(self) -> Thread:
-        # Check if CPU monitoring is enabled in configuration
-        cpu_monitoring_enabled = self.config.backpressure.cpu_monitoring_enabled
-        
-        if not cpu_monitoring_enabled:
-            logging_info("Backpressure CPU monitoring is disabled by configuration")
-            return None
+            self.maximum_load = maximum
 
+    def start_backpressure_monitor(self) -> Optional[Thread]:
         # Start the Backpressure monitor loop
         self.thread = Thread(target=self.backpressure_monitor_loop)
         self.thread.daemon = True  # This makes it a daemon thread
@@ -215,50 +196,54 @@ class BackpressureHandler:
         or if the service has been idle for too long (IDLE).
         """
         current_time = time.time()
-        self.update_last_data_message_time()
-        
+        last_event_delta = current_time - self.last_backpressure_event_time
         logging_info(
             "Backpressure: Check conditions, current=%s, max=%s, last_activity=%s",
-            self.current_parallel_executions,
-            self.parallel_workers,
-            current_time - self.last_data_message_time,
+            self.current_load,
+            self.maximum_load,
+            last_event_delta,
         )
 
         # Check for OVERLOAD condition
-        if self.current_parallel_executions >= self.parallel_workers - 1:
+        if self.current_load >= round(0.8 * self.maximum_load):
             # Check if the last backpressure event was not an overload
             if self.last_backpressure_event != ScalingRequestAlert.OVERLOAD:
                 # Trigger the overload event
                 await self.handle_backpressure_overload_event()
+                # update / reset time-window so that the OVERLOAD is not sent too often
                 self.last_backpressure_event_time = current_time
                 self.last_backpressure_event = ScalingRequestAlert.OVERLOAD
 
         # Check for IDLE condition
-        elif self.current_parallel_executions == 0:
+        elif self.current_load == 0:
             idle_duration = self.config.backpressure.idle_duration
             # Check if service has been idle for longer than the configured duration
-            if (current_time - self.last_data_message_time > idle_duration and
-                (current_time - self.last_backpressure_event_time > self.config.backpressure.time_window or
-                 self.last_backpressure_event != ScalingRequestAlert.IDLE)):
+            if (
+                last_event_delta > idle_duration
+                and self.last_backpressure_event == ScalingRequestAlert.IDLE
+            ):
 
                 logging_info(
                     "Backpressure: Service has been idle for %s seconds (threshold: %s seconds)",
-                    current_time - self.last_data_message_time,
-                    idle_duration
+                    last_event_delta,
+                    idle_duration,
                 )
 
                 # Trigger the idle event
                 await self._handle_backpressure_idle_event()
+                # update / reset time-window so that the IDLE is not sent too often
                 self.last_backpressure_event_time = current_time
+            else:
+                # Don't send IDLE right away when the usage drops to zero / below threshold, but wait for a while
                 self.last_backpressure_event = ScalingRequestAlert.IDLE
 
         # If neither OVERLOAD nor IDLE, and it's time for an update, send UPDATE event
-        elif (current_time - self.last_backpressure_event_time > self.config.backpressure.time_window):
+        elif last_event_delta > self.config.backpressure.time_window:
             _scaling_request: ScaleRequestV1 = ScaleRequestV1(
                 self.swarm_service_id,
                 self.swarm_task_id,
-                self.parallel_workers,
-                self.parallel_workers - self.current_parallel_executions,
+                self.maximum_load,
+                self.maximum_load - self.current_load,
                 ScalingRequestAlert.UPDATE,
             )
             # Address the message to any adapter capable of supporting BACKPRESSURE request
@@ -266,8 +251,12 @@ class BackpressureHandler:
             self.last_backpressure_event_time = current_time
             self.last_backpressure_event = ScalingRequestAlert.UPDATE
 
+        self.update_last_data_message_time()
+
     async def _backpressure_monitor(self):
         """Monitor the backpressure conditions and trigger events accordingly"""
+        # Check if CPU monitoring is enabled in configuration
+        cpu_monitoring_enabled = self.config.backpressure.cpu_monitoring_enabled
         _time_window_millis = self.config.backpressure.time_window
         _idle_duration_millis = self.config.backpressure.idle_duration
         _overload_duration_millis = self.config.backpressure.cpu_overload_duration
@@ -281,6 +270,7 @@ class BackpressureHandler:
         _cpu_usage_state = CPU_ACTIVE
         _cpu_usage_changed = time.time()
         while self._do_loop():
+            if cpu_monitoring_enabled:
                 _current_cpu_usage = psutil.cpu_percent(interval=None)
                 self.average_cpu_usage.add(_current_cpu_usage)
                 _average_cpu_usage = self.average_cpu_usage.get_average()
@@ -290,7 +280,6 @@ class BackpressureHandler:
                 #    _current_cpu_usage,
                 #    _average_cpu_usage,
                 #    _cpu_usage_state,
-            #    self.last_data_message_time,
                 #    self.last_backpressure_event,
                 #    self.last_backpressure_event_time,
                 # )
@@ -323,7 +312,6 @@ class BackpressureHandler:
                 elif (
                     _cpu_usage_state == CPU_IDLE
                     and _now - _cpu_usage_changed > _idle_duration_millis
-                and _now - self.last_data_message_time > _idle_duration_millis
                     and (
                         _now - self.last_backpressure_event_time > _time_window_millis
                         or self.last_backpressure_event != ScalingRequestAlert.IDLE
@@ -348,6 +336,10 @@ class BackpressureHandler:
                         await self.publish_backpressure_request(_scaling_request)
                         self.last_backpressure_event_time = _now
                         self.last_backpressure_event = ScalingRequestAlert.UPDATE
+            else:
+                # If CPU monitoring is disabled, just check the current load
+                await self.check_overload_condition()
+
             await asyncio.sleep(_monitor_interval)
 
     def backpressure_monitor_loop(self):
@@ -360,14 +352,12 @@ class BackpressureHandler:
         scaling_request: ScaleRequestV1 = ScaleRequestV1(
             self.swarm_service_id,
             self.swarm_task_id,
-            self.parallel_workers,
-            self.parallel_workers - self.current_parallel_executions,
+            self.maximum_load,
+            self.maximum_load - self.current_load,
             ScalingRequestAlert.OVERLOAD,
         )
         # Address the message to any management service instance capable of supporting BACKPRESSURE request
         await self.publish_backpressure_request(scaling_request)
-        # update / reset time-window so that the OVERLOAD is not sent too often
-        self.last_data_message_time = time.time()
 
     async def _handle_backpressure_idle_event(self):
         logging_warning("Backpressure: Service is idle.")
@@ -375,14 +365,12 @@ class BackpressureHandler:
         scaling_request: ScaleRequestV1 = ScaleRequestV1(
             self.swarm_service_id,
             self.swarm_task_id,
-            self.parallel_workers,
-            self.parallel_workers - self.current_parallel_executions,
+            self.maximum_load,
+            self.maximum_load - self.current_load,
             ScalingRequestAlert.IDLE,
         )
         # Address the message to any adapter capable of supporting BACKPRESSURE request
         await self.publish_backpressure_request(scaling_request)
-        # update / reset time-window so that the IDLE is not sent too often
-        self.last_data_message_time = time.time()
 
     async def publish_backpressure_request(self, scaling_request: ScaleRequestV1):
         # Publish the backpressure request to the management service
@@ -429,3 +417,14 @@ class BackpressureHandler:
             if BackpressureHandler._callback_list is not None:
                 BackpressureHandler._callback_list["_wrap_rabbit_mq_api"] = 1
             await await_future(asyncio.run_coroutine_threadsafe(_wrap_rabbit_mq_api(), self.loop))
+
+    def _do_loop(self) -> bool:
+        """
+        Helper function for unit tests to perform several loops only. Check if the loop should continue running.
+        Positive value of do_loop indicates the number of iterations left.
+        Negative value indicates the loop should run indefinitely.
+        """
+        _val = self.do_loop != 0
+        if self.do_loop > 0:
+            self.do_loop -= 1
+        return _val

amqp/config/amq_configuration.py

@@ -150,7 +150,7 @@ class Backpressure:
 
         :param config: config parser to read configuration values
         """
-        self.threshold_threads = config.getint(
+        self.threshold_load = config.getint(
             "CleverMicro-AMQ",
             self.PREFIX + "threshold",
             fallback=int(os.getenv("PARALLEL_WORKERS", 1)),

amqp/service/amq_message_handler.py

@@ -124,10 +124,10 @@ class DataMessageHandler:
         :return: DataResponse
         """
         # Increment the counter for parallel executions and check resource availability
-        self.backpressure_handler.increase_parallel_executions()
+        self.backpressure_handler.increase_current_load()
         await self.backpressure_handler.check_overload_condition()
         logging_info(
-            f"PARALLEL: Current Capacity [{self.backpressure_handler.current_parallel_executions}] of [{self.backpressure_handler.parallel_workers}]"
+            f"PARALLEL: Current Capacity [{self.backpressure_handler.current_load}] of [{self.backpressure_handler.maximum_load}]"
         )
         if message.reply_to:
             self.reply_to = message.reply_to
@@ -155,7 +155,7 @@ class DataMessageHandler:
         except Exception as e:
             logging_error(f"Request handler: {e}")
 
-        self.backpressure_handler.decrease_parallel_executions()
+        self.backpressure_handler.decrease_current_load()
         await self.backpressure_handler.check_overload_condition()
 
     async def reconstitute_data_message(
@@ -208,12 +208,12 @@ class DataMessageHandler:
         #             map_as_string(amq_message.trace_info()), context_with_span, context)
 
     def record_duration(self, start, delivery_tag):
-        global last_data_message_time
-        last_data_message_time = time.time()
+        global last_backpressure_event_time
+        last_backpressure_event_time = time.time()
         logging_info(
             "######[%s] Done, single ACK: %sms.",
             delivery_tag,
-            last_data_message_time - start,
+            last_backpressure_event_time - start,
         )
 
     async def send_reply(self, reply_to: str, response: DataResponse):

amqp/service/amq_service.py

@@ -83,24 +83,27 @@ class AMQService:
         logging.info("***********************************************")
         self.loop.run_forever()
 
-    def backpressure(self, current: int, maximum: int = -1):
+    def backpressure(self, current_availability: int, maximum: int = -1):
         """
         Send Backpressure event to the Management Service. The Backpressure logic determines the type of the event
-        based on the current and maximum values.
-        - OVERLOAD event is triggered immediately when the current value exceeds the maximum threshold, which is
+        based on the current_availability and maximum values.
+        - OVERLOAD event is triggered immediately when the current_availability value exceeds the maximum threshold, which is
         typically set to 80% of the maximum value.
-        - IDLE event is triggered when the current value drops below 20% of the maximum value and remains there for
+        - IDLE event is triggered when the current_availability value drops below 20% of the maximum value and remains there for
         a IDLE_WINDOW period of time (see BackpressureHandler).
         - UPDATE event is sent if neither OVERLOAD nor IDLE conditions are met, indicating that the backpressure is
         within acceptable limits.
-        :param current: Current value of the backpressure metric.
-        :param maximum: Maximum value of the backpressure metric. If undefined or set to lt 0, the maximum is set
-        according to the configuration value 'cm.backpressure.threshold'.
+        :param current_availability: Currently available caopacity.
+        :param maximum: Maximum value of the backpressure metric. If undefined or set to lt 0 (e.g. -1),
+        the maximum is than hgdetermined from max value of current_availability seen over the time.
         """
         if self.backpressure_handler is not None:
             if maximum < 0:
-                maximum = self.amq_configuration.backpressure.threshold_threads
-            self.backpressure_handler.update_backpressure_value(current, maximum)
+                maximum = self.amq_configuration.backpressure.threshold_load
+            asyncio.run_coroutine_threadsafe(
+                self.backpressure_handler.update_backpressure_value(current_availability, maximum),
+                loop=self.backpressure_handler.loop,
+            )
 
     def rpc(self, service_name: str, fq_method_name: str, **kwargs) -> Future:
         """

tests/adapter/test_backpressure_handler.py

@@ -13,9 +13,6 @@ from aio_pika import Exchange
 from aio_pika.abc import AbstractRobustChannel
 
 from amqp.adapter.backpressure_handler import (
-    RESOURCE_ACTIVE,
-    RESOURCE_OVERLOAD,
-    RESOURCE_UNSET,
     BackpressureHandler,
     RunningAverage,
     ScaleRequestV1,
@@ -289,38 +286,38 @@ class TestBackpressureHandler:
         assert handler.config == mock_config
         assert handler.swarm_service_id == "clever-amqp-service"
         assert handler.swarm_task_id == "python-adapter"
-        assert handler.parallel_workers == mock_config.backpressure.threshold_threads
+        assert handler.maximum_load == mock_config.backpressure.threshold_load
         assert handler.average_cpu_usage is None
 
-    def test_increase_parallel_executions(self, mock_channel, mock_loop, mock_config):
+    def test_increase_current_load(self, mock_channel, mock_loop, mock_config):
         """
-        Test the increase_parallel_executions method.
+        Test the increase_current_load method.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        initial_executions = handler.current_parallel_executions
-        handler.increase_parallel_executions()
-        assert handler.current_parallel_executions == initial_executions + 1
+        initial_load = handler.current_load
+        handler.increase_current_load()
+        assert handler.current_load == initial_load + 1
 
-    def test_decrease_parallel_executions(self, mock_channel, mock_loop, mock_config):
+    def test_decrease_current_load(self, mock_channel, mock_loop, mock_config):
         """
-        Test the decrease_parallel_executions method.
+        Test the decrease_current_load method.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.current_parallel_executions = 5
-        handler.decrease_parallel_executions()
-        assert handler.current_parallel_executions == 4
+        handler.current_load = 5
+        handler.decrease_current_load()
+        assert handler.current_load == 4
 
-        handler.current_parallel_executions = 0
-        handler.decrease_parallel_executions()
-        assert handler.current_parallel_executions == 0  # Should not go below 0
+        handler.current_load = 0
+        handler.decrease_current_load()
+        assert handler.current_load == 0  # Should not go below 0
 
-    def test_update_parallel_executions(self, mock_channel, mock_loop, mock_config):
+    def test_update_current_load(self, mock_channel, mock_loop, mock_config):
         """
-        Test the update_parallel_executions method.
+        Test the update_current_load method.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.update_parallel_executions(100)
-        assert handler.current_parallel_executions == 100
+        handler.update_current_load(100)
+        assert handler.current_load == 100
 
     def test_update_last_data_message_time(self, mock_channel, mock_loop, mock_config):
         """
@@ -330,7 +327,7 @@ class TestBackpressureHandler:
         with patch("time.time") as mock_time:
             mock_time.return_value = 12345
             handler.update_last_data_message_time()
-            assert handler.last_data_message_time == 12345
+            assert handler.last_backpressure_event_time == 12345
 
     def test_start_backpressure_monitor(self, mock_channel, mock_loop, mock_config):
         """
@@ -345,19 +342,25 @@ class TestBackpressureHandler:
     @pytest.mark.asyncio
     async def test_check_overload_condition_no_overload(self, mock_channel, mock_loop, mock_config):
         """
-        Test the check_overload_condition method when there is no overload.
+        Test the check_overload_condition method when there is no overload and only short time elapsed from last message
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.current_parallel_executions = 1
-        handler.parallel_workers = 5
+        handler.current_load = 1
+        handler.maximum_load = 5
         handler.last_backpressure_event = ScalingRequestAlert.UPDATE
         handler.publish_backpressure_request = AsyncMock()
+        handler.last_backpressure_event_time = 12340
         with patch("time.time") as mock_time:
             mock_time.return_value = 12345
-            with patch.object(handler, "handle_backpressure_overload_event") as mock_handle_overload:
+            with patch.object(
+                handler, "handle_backpressure_overload_event"
+            ) as mock_handle_overload:
                 await handler.check_overload_condition()
                 mock_handle_overload.assert_not_called()
-                if 12345 - handler.last_backpressure_event_time > mock_config.backpressure.time_window:
+                if (
+                    12345 - handler.last_backpressure_event_time
+                    > mock_config.backpressure.time_window
+                ):
                     handler.publish_backpressure_request.assert_called_once()
                     assert handler.last_backpressure_event == ScalingRequestAlert.UPDATE
                     assert handler.last_backpressure_event_time == 12345
@@ -370,7 +373,7 @@ class TestBackpressureHandler:
         Test the check_overload_condition method when there is an overload.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.current_parallel_executions = 9  # Assuming parallel_workers is 10
+        handler.current_load = 9  # Assuming maximum_load is 10
         handler.last_backpressure_event = ScalingRequestAlert.UPDATE
         handler.publish_backpressure_request = AsyncMock()
         with patch.object(handler, "handle_backpressure_overload_event") as mock_handle_overload:
@@ -390,7 +393,7 @@ class TestBackpressureHandler:
         Test the check_overload_condition method when the last event was already an overload.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.current_parallel_executions = 10
+        handler.current_load = 10
         handler.last_backpressure_event = ScalingRequestAlert.OVERLOAD
         handler.publish_backpressure_request = AsyncMock()
         with patch.object(handler, "handle_backpressure_overload_event") as mock_handle_overload:
@@ -418,7 +421,7 @@ class TestBackpressureHandler:
 
         # 1. Simulate an overload condition:
         handler.last_backpressure_event_time = 0  # Force event trigger
-        handler.last_data_message_time = 0
+        handler.last_backpressure_event_time = 0
         handler.do_loop = 1
         handler.config.backpressure.cpu_overload_duration = (
             -1
@@ -432,7 +435,7 @@ class TestBackpressureHandler:
         )  # Mock the RunningAverage in IDLE state
         handler.average_cpu_usage.is_filled = True  # Together with 0 values ensures IDLE state
         handler.last_backpressure_event_time = 0
-        handler.last_data_message_time = 0
+        handler.last_backpressure_event_time = 0
         handler.do_loop = 1
         handler.config.backpressure.idle_duration = (
             -1
@@ -445,7 +448,7 @@ class TestBackpressureHandler:
         handler._handle_backpressure_idle_event.call_count = 0
         handler.average_cpu_usage = RunningAverage(100)  # Mock the RunningAverage in pritine state
         handler.last_backpressure_event_time = 0
-        handler.last_data_message_time = 0
+        handler.last_backpressure_event_time = 0
         handler.do_loop = 1
         await handler._backpressure_monitor()
         assert (
@@ -465,7 +468,6 @@ class TestBackpressureHandler:
             mock_time.return_value = 12345
             await handler.handle_backpressure_overload_event()
         assert handler.publish_backpressure_request.call_count == 1
-        assert handler.last_data_message_time == 12345
 
     @pytest.mark.asyncio
     async def test_handle_backpressure_idle_event(self, mock_channel, mock_loop, mock_config):
@@ -478,12 +480,11 @@ class TestBackpressureHandler:
             mock_time.return_value = 12345
             await handler._handle_backpressure_idle_event()
         assert handler.publish_backpressure_request.call_count == 1
-        assert handler.last_data_message_time == 12345
 
     @pytest.mark.asyncio
-    async def test_check_resource_availability_overload(self, mock_channel, mock_loop, mock_config):
+    async def test_update_backpressure_value_overload(self, mock_channel, mock_loop, mock_config):
         """
-        Test the check_resource_availability method when resource usage is in OVERLOAD state.
+        Test the update_backpressure_value method when resource usage is in OVERLOAD state.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
         handler.handle_backpressure_overload_event = AsyncMock()
@@ -492,17 +493,15 @@ class TestBackpressureHandler:
 
         # Set up initial state
         handler.last_backpressure_event = ScalingRequestAlert.UPDATE
-        handler.last_backpressure_event_time = 0
-        handler._resource_usage_state = RESOURCE_ACTIVE  # Start with ACTIVE state
-        handler._resource_usage_changed = 0
+        handler.last_backpressure_event_time = 10  # time of last message
+        handler._resource_usage_changed = 10  # time of last change
 
         with patch("time.time") as mock_time:
             mock_time.return_value = 100
             # Call with resource usage above OVERLOAD threshold (90% of maximum)
-            await handler.check_resource_availability(95, 100)
+            await handler.update_backpressure_value(95, 100)
 
             # Debug output
-            print(f"Resource usage state: {handler._resource_usage_state}")
             print(f"Last backpressure event: {handler.last_backpressure_event}")
             print(f"Last backpressure event time: {handler.last_backpressure_event_time}")
             print(f"Time window: {mock_config.backpressure.time_window}")
@@ -513,12 +512,11 @@ class TestBackpressureHandler:
         handler.handle_backpressure_overload_event.assert_called_once()
         assert handler.last_backpressure_event == ScalingRequestAlert.OVERLOAD
         assert handler.last_backpressure_event_time == 100
-        assert handler._resource_usage_state == RESOURCE_OVERLOAD
 
     @pytest.mark.asyncio
-    async def test_check_resource_availability_idle(self, mock_channel, mock_loop, mock_config):
+    async def test_update_backpressure_value_idle(self, mock_channel, mock_loop, mock_config):
         """
-        Test the check_resource_availability method when resource usage is in IDLE state.
+        Test the update_backpressure_value method when resource usage is in IDLE state.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
         handler._handle_backpressure_idle_event = AsyncMock()
@@ -528,17 +526,16 @@ class TestBackpressureHandler:
         # Set up initial state
         handler.last_backpressure_event = ScalingRequestAlert.UPDATE
         handler.last_backpressure_event_time = 0
-        handler._resource_usage_state = RESOURCE_UNSET  # Start with UNSET state
         handler._resource_usage_changed = 0
 
         with patch("time.time") as mock_time:
             # First call to set state to IDLE
             mock_time.return_value = 50
-            await handler.check_resource_availability(10, 100)
+            await handler.update_backpressure_value(0, 10)
 
             # Second call after idle_duration has passed
             mock_time.return_value = 50 + mock_config.backpressure.idle_duration + 1
-            await handler.check_resource_availability(10, 100)
+            await handler.update_backpressure_value(0, 10)
 
         # Verify IDLE event was triggered
         handler._handle_backpressure_idle_event.assert_called_once()
@@ -548,9 +545,9 @@ class TestBackpressureHandler:
         )
 
     @pytest.mark.asyncio
-    async def test_check_resource_availability_update(self, mock_channel, mock_loop, mock_config):
+    async def test_update_backpressure_value_update(self, mock_channel, mock_loop, mock_config):
         """
-        Test the check_resource_availability method when resource usage is in ACTIVE state.
+        Test the update_backpressure_value method when resource usage is in ACTIVE state.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
         handler.publish_backpressure_request = AsyncMock()
@@ -564,13 +561,12 @@ class TestBackpressureHandler:
         with patch("time.time") as mock_time:
             mock_time.return_value = 100
             # Call with resource usage between thresholds
-            await handler.check_resource_availability(50, 100)
+            await handler.update_backpressure_value(50, 100)
 
         # Verify UPDATE event was triggered
         assert handler.publish_backpressure_request.call_count == 1
         assert handler.last_backpressure_event == ScalingRequestAlert.UPDATE
         assert handler.last_backpressure_event_time == 100
-        assert handler._resource_usage_state == RESOURCE_ACTIVE
 
     @pytest.mark.asyncio
     async def test_publish_backpressure_request_exchange_exists(
@@ -622,28 +618,28 @@ class TestBackpressureHandler:
         Test the update_backpressure_value method.
         """
         handler = BackpressureHandler(mock_channel, mock_loop, mock_config)
-        handler.update_parallel_executions = MagicMock()
+        handler.update_current_load = MagicMock()
         handler.update_last_data_message_time = MagicMock()
         handler.check_overload_condition = AsyncMock()
 
         # Test with current value and same maximum
-        await handler.update_backpressure_value(5, handler.parallel_workers)
-        handler.update_parallel_executions.assert_called_once_with(5)
+        await handler.update_backpressure_value(5, handler.maximum_load)
+        handler.update_current_load.assert_called_once_with(5)
         handler.update_last_data_message_time.assert_called_once()
         handler.check_overload_condition.assert_called_once()
 
         # Reset mocks
-        handler.update_parallel_executions.reset_mock()
+        handler.update_current_load.reset_mock()
         handler.update_last_data_message_time.reset_mock()
         handler.check_overload_condition.reset_mock()
 
         # Test with current value and different maximum
-        original_workers = handler.parallel_workers
+        original_workers = handler.maximum_load
         await handler.update_backpressure_value(3, original_workers + 5)
-        handler.update_parallel_executions.assert_called_once_with(3)
+        handler.update_current_load.assert_called_once_with(3)
         handler.update_last_data_message_time.assert_called_once()
         handler.check_overload_condition.assert_called_once()
-        assert handler.parallel_workers == original_workers + 5
+        assert handler.maximum_load == original_workers + 5
 
     @pytest.mark.asyncio
     async def test_check_overload_condition_idle(self, mock_channel, mock_loop, mock_config):
@@ -654,8 +650,8 @@ class TestBackpressureHandler:
         handler._handle_backpressure_idle_event = AsyncMock()
 
         # Set up initial state for IDLE condition
-        handler.current_parallel_executions = 0
-        handler.last_backpressure_event = ScalingRequestAlert.UPDATE
+        handler.current_load = 0
+        handler.last_backpressure_event = ScalingRequestAlert.IDLE
 
         with patch("time.time") as mock_time:
             # Set current time
@@ -663,11 +659,8 @@ class TestBackpressureHandler:
             mock_time.return_value = current_time
 
             # Set last data message time to be older than idle_duration
-            handler.last_data_message_time = (
-                current_time - mock_config.backpressure.idle_duration - 10
-            )
             handler.last_backpressure_event_time = (
-                current_time - mock_config.backpressure.time_window - 10
+                current_time - mock_config.backpressure.idle_duration - 10
             )
 
             # Call the method
@@ -687,8 +680,8 @@ class TestBackpressureHandler:
         handler.publish_backpressure_request = AsyncMock()
 
         # Set up initial state for UPDATE condition
-        handler.current_parallel_executions = 2
-        handler.parallel_workers = 10
+        handler.current_load = 2
+        handler.maximum_load = 10
         handler.last_backpressure_event = ScalingRequestAlert.IDLE  # Coming from IDLE state
 
         with patch("time.time") as mock_time:
@@ -720,8 +713,8 @@ class TestBackpressureHandler:
         thread = handler.start_backpressure_monitor()
 
         # Verify no thread was started
-        assert thread is None
-        assert not hasattr(handler, "thread") or handler.thread is None
+        assert thread is not None
+        assert hasattr(handler, "thread") or handler.thread is not None
 
     def test_start_backpressure_monitor_enabled(self, mock_channel, mock_loop, mock_config):
         """

tests/service/test_amq_service.py

@@ -1,8 +1,7 @@
 import unittest
-from unittest.mock import AsyncMock, MagicMock, Mock, patch
+from unittest.mock import AsyncMock, Mock, patch
 
 from amqp.config.amq_configuration import AMQAdapter, AMQConfiguration
-from amqp.model.model import DataMessage
 from amqp.service.amq_service import AMQService
 
 
@@ -14,6 +13,11 @@ class TestAMQService(unittest.IsolatedAsyncioTestCase):
         self.mock_adapter.route_mapping = {}
         self.mock_adapter.swarm_service_id = "test-swarm-id"
         self.mock_adapter.swarm_task_id = "test-task-id"
+        self.mock_adapter.consul_host = "consul"
+        self.mock_adapter.consul_port = 4500
+        self.mock_adapter.consul_counter_key = "services/ids/counter"
+        self.mock_adapter.consul_max_retries = 5
+        self.mock_adapter.consul_initial_retry_delay = 0.2
 
         self.mock_config = Mock(spec=AMQConfiguration)
         self.mock_config.amq_adapter = self.mock_adapter
@@ -29,7 +33,7 @@ class TestAMQService(unittest.IsolatedAsyncioTestCase):
 
         # Add backpressure configuration
         self.mock_backpressure = Mock()
-        self.mock_backpressure.threshold_threads = 10
+        self.mock_backpressure.threshold_load = 10
         self.mock_config.backpressure = self.mock_backpressure
 
         # Create service instance with mocked configuration
@@ -145,22 +149,6 @@ class TestAMQService(unittest.IsolatedAsyncioTestCase):
         # Verify that client was reinitialized
         mock_client.init.assert_called_once()
 
-    def test_send_message(self):
-        # Create mock message and future
-        mock_message = Mock(spec=DataMessage)
-        mock_message.id.return_value = "test-id"
-        mock_future = MagicMock()
-
-        # Setup mock message handler
-        self.service.amq_data_message_handler = Mock()
-        self.service.amq_data_message_handler.outstanding = {}
-
-        # Send message
-        self.service.send_message(mock_message, mock_future)
-
-        # Verify message was added to outstanding
-        self.assertEqual(self.service.amq_data_message_handler.outstanding["test-id"], mock_future)
-
     def test_remove_outstanding_future(self):
         # Setup mock message handler with outstanding message
         self.service.amq_data_message_handler = Mock()