Lambdaの非同期呼び出し
非同期Lambda呼び出しの特徴を理解し、イベントソース、リトライ、長時間処理やバッチ処理におけるメリットを習得します。
「Lambdaの非同期呼び出し」はCoddyKit上の無料Serverless AWS Lambda Developmentレッスンです。 これはレッスン1/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはServerless AWS Lambda Development学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Serverless AWS Lambda Developmentコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
What is Asynchronous Invocation?
Welcome! In serverless, functions can be invoked in different ways. An asynchronous invocation means the caller doesn't wait for the function to finish executing.
Think of it like sending a letter: you drop it in the mailbox, and you don't wait for the recipient to read it. You trust it will be delivered and processed later.
Sync vs. Async: The Key Difference
When you invoke a Lambda function synchronously, you wait for a response immediately. Your application pauses until Lambda returns a result or an error.
With asynchronous invocation, Lambda places the event in an internal queue and immediately returns a success message to the caller. The actual function execution happens in the background.
How Asynchronous Invocation Works
When an event triggers an asynchronous Lambda invocation:
- Lambda receives the event from the caller (e.g., S3, SNS).
- It places the event in an internal queue.
- Lambda sends an immediate success response to the caller.
- Later, Lambda retrieves the event from the queue and invokes your function.
- The function processes the event, and any output is discarded.
Invocation Types in Practice
When you invoke a Lambda function directly via the AWS SDK or CLI, you specify an InvocationType parameter:
RequestResponse: For synchronous invocations (you wait for a response).Event: For asynchronous invocations (fire-and-forget).DryRun: To validate parameters without invoking.
Many AWS services (like S3, SNS, EventBridge) inherently invoke Lambda asynchronously when configured as triggers.
Benefits: Decoupling and Scalability
Asynchronous invocations offer significant advantages:
- Decoupling: The caller doesn't depend on the function's immediate response. It can continue its work without waiting.
- Scalability: Lambda can buffer events in its internal queue during traffic spikes, preventing your function from being overwhelmed and ensuring events are eventually processed.
- Resilience: If your function fails, Lambda can automatically retry the invocation.
Ideal for Long-Running Tasks
Asynchronous invocation is perfect for tasks that might take a while to complete, like:
- Processing large files uploaded to S3.
- Sending email notifications.
- Transcoding videos.
- Updating multiple databases.
The client doesn't need to wait for these operations, improving user experience and application responsiveness.
Asynchronous Retries Explained
By default, if an asynchronously invoked Lambda function fails, Lambda automatically retries the invocation twice, with an exponential backoff between attempts.
This built-in retry mechanism enhances the reliability of your serverless applications by handling transient errors without manual intervention.
Configuring Retry Behavior
You can customize the retry behavior for asynchronous invocations:
- Maximum event age: How long Lambda should keep an event in the queue before discarding it (default: 6 hours).
- Maximum retry attempts: How many times Lambda should retry the function (0 to 2 attempts).
These settings help control how long your system tries to process a failed event.
Example: Processing an Uploaded Image
Imagine a user uploads an image to an S3 bucket. You want to resize it and add a watermark.
You can configure the S3 bucket to trigger a Lambda function whenever a new image is uploaded. S3 will asynchronously invoke your Lambda, which then processes the image. The user doesn't wait for the resizing to complete.
Lambda Function for Async Processing
Here's a simple Python Lambda function that could be invoked asynchronously. It simulates a long-running task.
When invoked asynchronously, the caller won't wait for the time.sleep() to finish.
import json
import time
def lambda_handler(event, context):
print("Received event:", json.dumps(event, indent=2))
# Simulate a long-running task
print("Starting long-running task...")
time.sleep(5) # Pause for 5 seconds
print("Task completed!")
# For async invocations, the return value is usually ignored
return {
'statusCode': 200,
'body': json.dumps('Processing complete!')
}Quick Check on Async
You've learned about the core concepts of asynchronous Lambda invocations.
Which of the following is a primary benefit of using asynchronous Lambda invocations?
Recap: Asynchronous Power
Great job! You've mastered the basics of asynchronous Lambda invocations.
- They allow callers to "fire-and-forget" events.
- Lambda uses an internal queue for processing.
- Benefits include decoupling, scalability, and handling long-running tasks.
- Built-in retry mechanisms enhance reliability.
This pattern is fundamental for building robust and scalable event-driven serverless applications. Next, we'll look at handling failures effectively with Dead Letter Queues!
よくある質問
「Lambdaの非同期呼び出し」レッスンは無料ですか？
はい。「Lambdaの非同期呼び出し」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Serverless AWS Lambda Developmentコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Serverless AWS Lambda Developmentコースには全4レッスンが含まれています。
「Lambdaの非同期呼び出し」で何を学びますか？
非同期Lambda呼び出しの特徴を理解し、イベントソース、リトライ、長時間処理やバッチ処理におけるメリットを習得します。 ブラウザで直接実行するハンズオンコードでServerless AWS Lambda Developmentを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
Serverless AWS Lambda Developmentを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのServerless AWS Lambda Developmentは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン1/4です。
「Lambdaの非同期呼び出し」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このServerless AWS Lambda Developmentレッスンでコードを書いて実行できますか？
はい。すべてのServerless AWS Lambda Developmentレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。