Prevent empty worker loop if no SQS queues are available

Author: Schweigi

README.md

@@ -168,6 +168,7 @@ The following settings can be used to fine tune django-eb-sqs. Copy them into yo
 - EB_AWS_REGION (`us-east-1`): The AWS region to use when working with SQS.
 - EB_SQS_MAX_NUMBER_OF_MESSAGES (`10`): The maximum number of messages to read in a single call from SQS (<= 10).
 - EB_SQS_WAIT_TIME_S (`2`): The time to wait (seconds) when receiving messages from SQS.
+- NO_QUEUES_WAIT_TIME_S (`5`): The time a workers waits if there are no SQS queues available to process.
 - EB_SQS_AUTO_ADD_QUEUE (`False`): If queues should be added automatically to AWS if they don't exist.
 - EB_SQS_QUEUE_MESSAGE_RETENTION (`1209600`): The value (in seconds) to be passed to MessageRetentionPeriod parameter, when creating a queue (only relevant in case EB_SQS_AUTO_ADD_QUEUE is set to True).
 - EB_SQS_QUEUE_VISIBILITY_TIMEOUT (`300`): The value (in seconds) to be passed to VisibilityTimeout parameter, when creating a queue (only relevant in case EB_SQS_AUTO_ADD_QUEUE is set to True).

eb_sqs/settings.py

@@ -6,6 +6,7 @@
 
 MAX_NUMBER_OF_MESSAGES = getattr(settings, 'EB_SQS_MAX_NUMBER_OF_MESSAGES', 10)  # type: int
 WAIT_TIME_S = getattr(settings, 'EB_SQS_WAIT_TIME_S', 2)  # type: int
+NO_QUEUES_WAIT_TIME_S = getattr(settings, 'NO_QUEUES_WAIT_TIME_S', 5)  # type: int
 
 AUTO_ADD_QUEUE = getattr(settings, 'EB_SQS_AUTO_ADD_QUEUE', False)  # type: bool
 QUEUE_PREFIX = getattr(settings, 'EB_SQS_QUEUE_PREFIX', 'eb-sqs-')  # type: str

eb_sqs/worker/service.py

@@ -2,6 +2,7 @@
 
 import logging
 from datetime import timedelta
+from time import sleep
 
 import boto3
 from botocore.config import Config
@@ -51,6 +52,7 @@ def process_queues(self, queue_names):
         worker = WorkerFactory.default().create()
 
         logger.info('[django-eb-sqs] WAIT_TIME_S = {}'.format(settings.WAIT_TIME_S))
+        logger.info('[django-eb-sqs] NO_QUEUES_WAIT_TIME_S = {}'.format(settings.NO_QUEUES_WAIT_TIME_S))
         logger.info('[django-eb-sqs] MAX_NUMBER_OF_MESSAGES = {}'.format(settings.MAX_NUMBER_OF_MESSAGES))
         logger.info('[django-eb-sqs] AUTO_ADD_QUEUE = {}'.format(settings.AUTO_ADD_QUEUE))
         logger.info('[django-eb-sqs] QUEUE_PREFIX = {}'.format(settings.QUEUE_PREFIX))
@@ -68,7 +70,10 @@ def process_queues(self, queue_names):
                 ))
 
             logger.debug('[django-eb-sqs] Processing {} queues'.format(len(queues)))
-            self.process_messages(queues, worker, static_queues)
+            if len(queues) == 0:
+                sleep(settings.NO_QUEUES_WAIT_TIME_S)
+            else:
+                self.process_messages(queues, worker, static_queues)
 
             if timezone.now() - timedelta(seconds=settings.MIN_HEALTHCHECK_WRITE_PERIOD_S) > last_healthcheck_time:
                 self.write_healthcheck_file()

setup.py

@@ -6,7 +6,7 @@
 
 setup(
     name='django-eb-sqs',
-    version='1.33',
+    version='1.34',
     package_dir={'eb_sqs': 'eb_sqs'},
     include_package_data=True,
     packages=find_packages(),