Files
amq-adapter-python/amqp/adapter/backpressure_handler.py
T
Stanislav Hejny 3150dc9907 feat: add toggle for CPU monitoring in backpressure handler
Co-authored-by: aider (openrouter/openai/o3-mini-high) <aider@aider.chat>
2025-07-11 23:38:01 +01:00

357 lines
15 KiB
Python

import asyncio
import json
import time
from asyncio import AbstractEventLoop
from threading import Thread
import psutil
from aio_pika import Message
from aio_pika.abc import AbstractRobustChannel
from amqp.adapter.logging_utils import logging_info, logging_warning
from amqp.config.amq_configuration import AMQConfiguration
from amqp.model.model import ScalingRequestAlert
from amqp.router.utils import await_future, await_result
CPU_IDLE, CPU_ACTIVE, CPU_OVERLOAD = 0, 1, 2
IDLE_THRESHOLD, OVERLOAD_THRESHOLD = 0.15, 0.90
RESOURCE_UNSET, RESOURCE_IDLE, RESOURCE_ACTIVE, RESOURCE_OVERLOAD = -1, 0, 1, 2
class ScaleRequestV1:
def __init__(
self,
serviceId: str,
taskId: str,
maxAvailability: int,
currentAvailability: int,
requestType: ScalingRequestAlert,
):
self.version = 1 # Version of the request, currently 1
self.serviceId = serviceId
self.taskId = taskId
self.maxAvailability = maxAvailability
self.currentAvailability = currentAvailability
self.requestType = requestType
self.thread = None
def to_json(self) -> str:
"""Converts the object to a JSON string matching the Java structure"""
return json.dumps(
{
"version": self.version,
"serviceId": self.serviceId,
"taskId": self.taskId,
"maxAvailability": self.maxAvailability,
"currentAvailability": self.currentAvailability,
"requestType": self.requestType.value, # Using .value for Enum serialization
},
indent=2,
)
class RunningAverage:
"""
A class to maintain a running average of the last N values.
The intended use is to track CPU usage over time window, that is directly related to sample rate and window size.
This is the reason why the constructor takes the number of items to store, calculated as window size / sample rate
Initial_value is for unit test to emulate OVERLOAD or IDLE condition.
"""
def __init__(self, num_items, initial_value=0):
self.buffer = [initial_value] * num_items # Fixed-size array
self.pointer = 0 # Current position in array
self.num_items = num_items # Maximum number of items to store
self.is_filled = False # Track if buffer is fully filled
def add(self, value):
# Store the value at current pointer position
self.buffer[self.pointer] = value
# Move pointer to next position with wrap-around
self.pointer += 1
if self.pointer >= self.num_items:
self.pointer = 0
self.is_filled = True
def get_average(self):
# Determine how many items we should average
count = self.num_items if self.is_filled else self.pointer
if count == 0:
return 0.0 # Avoid division by zero
return sum(self.buffer) / count
def get_current_values(self):
"""Returns the values in chronological order (oldest first)"""
if not self.is_filled:
return self.buffer[: self.pointer]
return self.buffer[self.pointer :] + self.buffer[: self.pointer]
class BackpressureHandler:
# Track the number of messages currently being processed
current_parallel_executions = 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
# _callback_list is used in unit tests to record the invoked callbacks
_callback_list = None
def __init__(
self,
channel: AbstractRobustChannel,
loop: AbstractEventLoop,
config: AMQConfiguration,
):
self.lock = None
self.channel = channel
self.loop = loop
self.config = config
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.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"""
logging_info(
"Backpressure: Increase parallel executions, current=%s",
self.current_parallel_executions,
)
self.current_parallel_executions += 1
def decrease_parallel_executions(self):
"""Decrease the number of parallel executions"""
logging_info(
"Backpressure: Decrease parallel executions, current=%s",
self.current_parallel_executions,
)
if self.current_parallel_executions > 0:
self.current_parallel_executions -= 1
def update_parallel_executions(self, count: int):
"""Update the number of parallel executions"""
self.current_parallel_executions = count
def update_last_data_message_time(self):
logging_info("Backpressure: Update last data message time")
"""Update the last data message time"""
self.last_data_message_time = time.time()
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
# Start the Backpressure monitor loop
self.thread = Thread(target=self.backpressure_monitor_loop)
self.thread.daemon = True # This makes it a daemon thread
self.thread.start()
return self.thread
async def check_overload_condition(self):
"""Check if the current parallel executions exceed the limit"""
self.update_last_data_message_time()
logging_info(
"Backpressure: Check overload condition, current=%s, max=%s",
self.current_parallel_executions,
self.parallel_workers,
)
if self.current_parallel_executions >= self.parallel_workers - 1:
# 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()
self.last_backpressure_event_time = time.time()
self.last_backpressure_event = ScalingRequestAlert.OVERLOAD
async def _backpressure_monitor(self):
"""Monitor the backpressure conditions and trigger events accordingly"""
_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
_monitor_interval = 0.5 # Monitor every 500ms
CPU_IDLE, CPU_ACTIVE, CPU_OVERLOAD = 0, 1, 2
IDLE_THRESHOLD, OVERLOAD_THRESHOLD = 15, 90
if self.average_cpu_usage is None:
self.average_cpu_usage = RunningAverage(
int(max(_overload_duration_millis, _idle_duration_millis) // _monitor_interval)
)
_cpu_usage_state = CPU_ACTIVE
_cpu_usage_changed = time.time()
while self._do_loop():
_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()
_now = time.time()
# logging_info(
# "Backpressure: current CPU[pct]=%s, avg=%s, state=%s, last dataMsg=%s, last event=%s, last eventTime=%s",
# _current_cpu_usage,
# _average_cpu_usage,
# _cpu_usage_state,
# self.last_data_message_time,
# self.last_backpressure_event,
# self.last_backpressure_event_time,
# )
if _average_cpu_usage < IDLE_THRESHOLD:
if _cpu_usage_state != CPU_IDLE:
_cpu_usage_changed = _now
_cpu_usage_state = CPU_IDLE
elif _average_cpu_usage > OVERLOAD_THRESHOLD:
if _cpu_usage_state != CPU_OVERLOAD:
_cpu_usage_changed = _now
_cpu_usage_state = CPU_OVERLOAD
else:
if _cpu_usage_state != CPU_ACTIVE:
_cpu_usage_changed = _now
_cpu_usage_state = CPU_ACTIVE
# Check if the current time exceeds the last backpressure event time
if (
_cpu_usage_state == CPU_OVERLOAD
and _now - _cpu_usage_changed > _overload_duration_millis
and (
_now - self.last_backpressure_event_time > _time_window_millis
or self.last_backpressure_event != ScalingRequestAlert.OVERLOAD
)
):
# Trigger the overload event
await self.handle_backpressure_overload_event()
self.last_backpressure_event_time = _now
self.last_backpressure_event = ScalingRequestAlert.OVERLOAD
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
)
):
# Trigger the idle event
await self._handle_backpressure_idle_event()
self.last_backpressure_event = ScalingRequestAlert.IDLE
self.last_backpressure_event_time = _now
else:
# Trigger update event
if _now - self.last_backpressure_event_time > _time_window_millis:
# Trigger the update event
_scaling_request: ScaleRequestV1 = ScaleRequestV1(
self.swarm_service_id,
self.swarm_task_id,
100,
_average_cpu_usage,
ScalingRequestAlert.UPDATE,
)
# Address the message to any adapter capable of supporting BACKPRESSURE request
await self.publish_backpressure_request(_scaling_request)
self.last_backpressure_event_time = _now
self.last_backpressure_event = ScalingRequestAlert.UPDATE
await asyncio.sleep(_monitor_interval)
def backpressure_monitor_loop(self):
_loop = asyncio.new_event_loop()
_loop.run_until_complete(self._backpressure_monitor())
async def handle_backpressure_overload_event(self):
logging_warning("Backpressure: Capacity close to depleted!")
# Send an Overload event to the Management service
scaling_request: ScaleRequestV1 = ScaleRequestV1(
self.swarm_service_id,
self.swarm_task_id,
self.parallel_workers,
self.parallel_workers - self.current_parallel_executions,
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.")
# Send an Idle event to the Management service
scaling_request: ScaleRequestV1 = ScaleRequestV1(
self.swarm_service_id,
self.swarm_task_id,
self.parallel_workers,
self.parallel_workers - self.current_parallel_executions,
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
logging_info(
f"Publishing backpressure for {scaling_request.serviceId} with request type {scaling_request.requestType}"
)
if not self.exchange:
async def _wrap_rabbit_mq_api_init(channel):
_exchange = await channel.get_exchange(name="cleverthis.clevermicro.management")
return _exchange
if BackpressureHandler._callback_list is not None:
BackpressureHandler._callback_list["_wrap_rabbit_mq_api_init"] = 1
self.exchange = await await_result(
asyncio.run_coroutine_threadsafe(_wrap_rabbit_mq_api_init(self.channel), self.loop)
)
if self.exchange:
async def _wrap_rabbit_mq_api():
if not self.channel.is_closed:
binary_content: bytes = scaling_request.to_json().encode("utf-8")
pika_message: Message = Message(
body=binary_content,
content_encoding="utf-8",
delivery_mode=2,
content_type="application/octet-stream",
headers=None,
priority=0,
correlation_id=None,
)
await self.exchange.publish(
message=pika_message, routing_key="backpressure-scaling-v1"
)
logging_info(
"Service Message Published to %s, msg: %s",
self.exchange.name,
str(binary_content),
)
return True
return False
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))