ffsshhttiikk What I do
- Implement reliable message publishing and consuming
- Handle message ordering and deduplication
- Use dead letter queues for failed messages
- Implement retry with exponential backoff
- Use topic exchanges for pub/sub patterns
- Handle consumer groups and load balancing
- Design for at-least-once or exactly-once semantics
- Monitor queue health and lag
When to use me
When implementing message queue systems (RabbitMQ, Kafka, SQS).
RabbitMQ Patterns
import pika
import json
from typing import Callable
from dataclasses import dataclass
from datetime import datetime
@dataclass
class Message:
id: str
type: str
payload: dict
timestamp: datetime
retry_count: int = 0
class RabbitMQPublisher:
def __init__(
self,
host: str = "localhost",
port: int = 5672,
username: str = "guest",
password: str = "guest",
) -> None:
self.host = host
self.port = port
self.credentials = pika.PlainCredentials(username, password)
self.connection = None
self.channel = None
def connect(self):
self.connection = pika.BlockingConnection(
pika.ConnectionParameters(
host=self.host,
port=self.port,
credentials=self.credentials,
heartbeat=600,
blocked_connection_timeout=300,
)
)
self.channel = self.connection.channel()
# Declare exchanges
self.channel.exchange_declare(
exchange='events',
exchange_type='topic',
durable=True
)
# Declare dead letter exchange
self.channel.exchange_declare(
exchange='events.dlx',
exchange_type='direct',
durable=True
)
def publish(
self,
routing_key: str,
message: Message,
exchange: str = 'events'
) -> None:
if not self.connection or self.connection.is_closed:
self.connect()
properties = pika.BasicProperties(
delivery_mode=2, # Persistent
content_type='application/json',
message_id=message.id,
timestamp=int(message.timestamp.timestamp()),
headers={
'retry_count': message.retry_count,
'x-dead-letter-exchange': 'events.dlx',
'x-dead-letter-routing-key': f'{routing_key}.dlq',
}
)
self.channel.basic_publish(
exchange=exchange,
routing_key=routing_key,
body=json.dumps(message.__dict__),
properties=properties,
)
def close(self):
if self.connection and not self.connection.is_closed:
self.connection.close()
class RabbitMQConsumer:
def __init__(
self,
queue_name: str,
handler: Callable[[Message], bool],
prefetch_count: int = 10,
) -> None:
self.queue_name = queue_name
self.handler = handler
self.prefetch_count = prefetch_count
def start(self):
connection = pika.BlockingConnection(
pika.ConnectionParameters(host='localhost')
)
channel = connection.channel()
# Declare queue with dead letter config
channel.queue_declare(
queue=self.queue_name,
durable=True,
arguments={
'x-dead-letter-exchange': 'events.dlx',
'x-dead-letter-routing-key': f'{self.queue_name}.dlq',
'x-message-ttl': 86400000, # 24 hours
}
)
# Dead letter queue
channel.queue_declare(
queue=f'{self.queue_name}.dlq',
durable=True,
)
channel.basic_qos(prefetch_count=self.prefetch_count)
channel.basic_consume(
queue=self.queue_name,
)
print(f'Consumer started on queue: {self.queue_name}')
channel.start_consuming()
def _handle_message(self, channel, method, properties, body):
try:
message = Message(**json.loads(body))
success = self.handler(message)
if success:
channel.basic_ack(delivery_tag=method.delivery_tag)
else:
# Requeue for retry
channel.basic_nack(
delivery_tag=method.delivery_tag,
requeue=False,
)
except Exception as e:
print(f"Error processing message: {e}")
channel.basic_nack(
delivery_tag=method.delivery_tag,
requeue=False,
)
Kafka Patterns
from kafka import KafkaProducer, KafkaConsumer
from kafka.errors import KafkaError
import json
class KafkaPublisher:
def __init__(self, bootstrap_servers: list) -> None:
self.producer = KafkaProducer(
bootstrap_servers=bootstrap_servers,
value_serializer=lambda v: json.dumps(v).encode('utf-8'),
key_serializer=lambda k: k.encode('utf-8') if k else None,
acks='all', # Wait for all replicas
retries=3,
retry_backoff_ms=500,
linger_ms=10, # Batch messages
batch_size=16384,
)
def publish(
self,
topic: str,
key: str,
value: dict,
partition_key: str = None
) -> None:
try:
future = self.producer.send(
topic,
key=key,
value=value,
timestamp_ms=int(datetime.utcnow().timestamp() * 1000),
)
# Wait for confirmation
record_metadata = future.get(timeout=10)
print(f"Message sent to {record_metadata.topic}[{record_metadata.partition}]")
except KafkaError as e:
print(f"Failed to send message: {e}")
raise
class KafkaConsumer:
def __init__(
self,
bootstrap_servers: list,
group_id: str,
topics: list,
auto_offset_reset: str = 'earliest',
) -> None:
self.consumer = KafkaConsumer(
*topics,
bootstrap_servers=bootstrap_servers,
group_id=group_id,
auto_offset_reset=auto_offset_reset,
enable_auto_commit=False,
value_deserializer=lambda v: json.loads(v.decode('utf-8')),
key_deserializer=lambda k: k.decode('utf-8') if k else None,
)
def consume(self, handler: callable):
for message in self.consumer:
try:
handler(
topic=message.topic,
partition=message.partition,
offset=message.offset,
key=message.key,
value=message.value,
)
# Manual commit after successful processing
self.consumer.commit()
except Exception as e:
print(f"Error processing message: {e}")
# Implement retry logic or dead letter
Retry with Exponential Backoff
import time
from functools import wraps
def retry_with_backoff(
max_retries: int = 3,
initial_delay: float = 1.0,
max_delay: float = 60.0,
exponential_base: float = 2.0,
):
def decorator(func):
@wraps(func)
def wrapper(*args, **kwargs):
retries = 0
delay = initial_delay
while True:
try:
return func(*args, **kwargs)
except Exception as e:
if retries >= max_retries:
raise
retries += 1
time.sleep(delay)
delay = min(delay * exponential_base, max_delay)
print(f"Retry {retries}/{max_retries} after {delay:.2f}s")
return wrapper
return decorator
SQS with Lambda
import boto3
import json
from datetime import datetime
sqs = boto3.client('sqs')
queue_url = 'https://sqs.us-east-1.amazonaws.com/123456789012/my-queue'
def send_message(message: dict, delay_seconds: int = 0) -> str:
response = sqs.send_message(
QueueUrl=queue_url,
MessageBody=json.dumps(message),
DelaySeconds=delay_seconds,
MessageAttributes={
'timestamp': {
'StringValue': datetime.utcnow().isoformat(),
'DataType': 'String',
}
}
)
return response['MessageId']
def receive_messages(max_messages: int = 10) -> list:
response = sqs.receive_message(
QueueUrl=queue_url,
MaxNumberOfMessages=max_messages,
WaitTimeSeconds=20,
MessageAttributeNames=['All'],
)
return response.get('Messages', [])
def delete_message(receipt_handle: str):
sqs.delete_message(
QueueUrl=queue_url,
ReceiptHandle=receipt_handle,
)