when to use AWS sync client vs AWS Async client
System Design practice on Codemia
Work through 120+ system design problems with detailed solutions, from rate limiters to multi-region storage.
In the landscape of cloud computing, AWS (Amazon Web Services) provides a suite of tools and services that cater to a vast array of application requirements. Among these tools, the AWS SDK (Software Development Kit) provides both synchronous and asynchronous clients for various services. Choosing between these two can significantly impact the architecture and performance of your application. Here, we delve into the technical nuances of using AWS sync and async clients and outline scenarios where one might be preferred over the other.
Understanding Sync vs. Async Clients
Before delving into their specific applications, it's crucial to understand what synchronous and asynchronous operations entail in the context of programming:
- Synchronous Operations (Sync): These operations block the executing thread until the task is completed. For example, if a function makes a synchronous API call, the code execution pauses until a response is received.
- Asynchronous Operations (Async): In contrast, asynchronous operations do not block the executing thread. When an async call is made, the operation can progress in the background, allowing the execution of other tasks without waiting for a response.
AWS Sync Client
Characteristics and Use-Cases
- Blocking I/O Operations: AWS sync clients execute requests and wait for their responses. These are typical in scenarios where subsequent operations depend on the result of the current API call.
- Simplified Code Logic: Sync clients can lead to more straightforward code since operations are completed sequentially, eliminating the complexity associated with callback management.
- Suitable for Smaller Applications: For applications with low traffic or infrequent requests, the performance overhead introduced by blocking calls might not be significant.
- Example Use-Case:
- Non-Blocking I/O Operations: AWS async clients facilitate non-blocking requests, allowing applications to handle I/O-related tasks more efficiently.
- Enhanced Performance: The ability to perform multiple operations concurrently without waiting for individual calls can significantly enhance the throughput, especially in high-load environments.
- Ideal for Scalable Applications: Async clients are better suited for cloud-native, microservices-oriented, or event-driven architectures that leverage concurrency.
- Example Use-Case:
- Async: Minimizes waiting time, leading to better resource utilization and faster response times in I/O-bound operations.
- Sync: May lead to idle resources as operations are performed sequentially.
- Async: Requires understanding and handling of asynchronous paradigms, which can introduce complexity in error handling and debugging.
- Sync: Easier to debug and maintain due to predictable, linear execution flow.
- Async: Generally consumes fewer resources per operation, allowing better scalability.
- Sync: Each request may block its thread, potentially requiring more threads for high concurrency.
Related reading
- When to use dynamodb.client, dynamodb.resource and dynamodb.Table?
- Where are AWS CodeDeploy Deployment logs found?
- Where can I log debug Velocity Template Language VTL in AWS AppSync?
- Where can I see tables for RDS instances in AWS console?
- When to use promise over async or packaged_task?
- When to use recursive mutex?
- Where can you change the batch size for an SQS queue that triggers an AWS Lambda function?
- where do I keep my amazon .pem file on a mac

System Design Fundamentals
Build a strong foundation in designing scalable, reliable distributed systems.
View the courseTrack what you have practised
A free account saves your progress, solutions and study plan across every problem on Codemia.
System Design practice on Codemia
Work through 120+ system design problems with detailed solutions, from rate limiters to multi-region storage.