fd0cb8e98f
* Started to play around with restarting from last processed After a failure the KCL would instead restart from what the ShardConsumer says it last processed. * Extracted the InternalSubscriber to its own class Extracted the InternalSubscriber to ShardConsumerSubscriber to make testing easier. Added tests for the ShardConsumerSubscriber that verifies error handling and other components of the class. Added tests that verify the restart from behavior. * Moved the ProcessRecordsInputMatcher to its own class * Initial changes to for restarting of the PrefetchRecordsPublisher * Remove code coverage configuration * Switched to using explicit locks to deal with blocking queue When the blocking queue is full it would normally enter into a fully parked state, but would continue to hold the lock. This changes the process to only block for a second when attempting to enqueue a response, and if it doesn't succeed check to see if it's been reset before attempting again. * Changed locking around the restart, and how fetcher gets updated Changed the locking around the restart to use a reader/writer lock instead of single lock with a yield. Changed how the fetcher is reset to not restart from an advanceIteratorTo which would retrieve a new shard iterator. Instead the resetIterator method takes both the iterator to start from, the last accepted sequence number, and the initial position. * Changed test to ensure that PositionResetException is thrown Changed the test to wait for the queue to reach capacity before restarting the PrefetchRecordsPublisher. This should mostly ensure that calling restartFrom will trigger a throw of a PositionResetException. Added @VisibleFortest on the queue since it was already being used in testing. * Move to snapshot * Ensure that only one thread can be sending data at a time In the test the TestPublisher is accessed from two threads: the test thread, and the dispatch thread. Both have the possibility of calling send() under certain conditions. This changes it so that only one of the threads can actively be sending data at a time. TestPublisher#requested was changed to volatile to ensure that calling cancel can correctly set it to zero. * Block the test until the blocking thread is in control This test is somewhat of an odd case as it intends to test what happens when nothing is dispatched to the ShardConsumerSubcriber for some amount of time, but data is queued for dispatch. To do this we block the single thread of the executor with a lock to ensure that items pile up in the queue so that should the restart work incorrectly we will see lost data. |
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Amazon Kinesis Client Library for Java
The Amazon Kinesis Client Library for Java (Amazon KCL) enables Java developers to easily consume and process data from Amazon Kinesis.
Recommended Upgrade for All Users of the 2.x Amazon Kinesis Client
⚠️ It's highly recommended for users of version 2.0 of the Amazon Kinesis Client to upgrade to version 2.0.3 or later. A bug has been identified in versions prior to 2.0.3 that could cause records to be delivered to the wrong record processor.
ℹ️ Amazon Kinesis Client versions 1.x are not impacted.
Please open an issue if you have any questions.
Features
- Provides an easy-to-use programming model for processing data using Amazon Kinesis
- Helps with scale-out and fault-tolerant processing
Getting Started
- Sign up for AWS — Before you begin, you need an AWS account. For more information about creating an AWS account and retrieving your AWS credentials, see AWS Account and Credentials in the AWS SDK for Java Developer Guide.
- Sign up for Amazon Kinesis — Go to the Amazon Kinesis console to sign up for the service and create an Amazon Kinesis stream. For more information, see Create an Amazon Kinesis Stream in the Amazon Kinesis Developer Guide.
- Minimum requirements — To use the Amazon Kinesis Client Library, you'll need Java 1.8+. For more information about Amazon Kinesis Client Library requirements, see Before You Begin in the Amazon Kinesis Developer Guide.
- Using the Amazon Kinesis Client Library — The best way to get familiar with the Amazon Kinesis Client Library is to read Developing Record Consumer Applications in the Amazon Kinesis Developer Guide.
Building from Source
After you've downloaded the code from GitHub, you can build it using Maven. To disable GPG signing in the build, use this command: mvn clean install -Dgpg.skip=true
Integration with the Kinesis Producer Library
For producer-side developers using the Kinesis Producer Library (KPL), the KCL integrates without additional effort. When the KCL retrieves an aggregated Amazon Kinesis record consisting of multiple KPL user records, it will automatically invoke the KPL to extract the individual user records before returning them to the user.
Amazon KCL support for other languages
To make it easier for developers to write record processors in other languages, we have implemented a Java based daemon, called MultiLangDaemon that does all the heavy lifting. Our approach has the daemon spawn a sub-process, which in turn runs the record processor, which can be written in any language. The MultiLangDaemon process and the record processor sub-process communicate with each other over STDIN and STDOUT using a defined protocol. There will be a one to one correspondence amongst record processors, child processes, and shards. For Python developers specifically, we have abstracted these implementation details away and expose an interface that enables you to focus on writing record processing logic in Python. This approach enables KCL to be language agnostic, while providing identical features and similar parallel processing model across all languages.
Using the KCL
The recommended way to use the KCL for Java is to consume it from Maven.
Version 2.x
<dependency>
<groupId>software.amazon.kinesis</groupId>
<artifactId>amazon-kinesis-client</artifactId>
<version>2.1.1</version>
</dependency>
Version 1.x
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>amazon-kinesis-client</artifactId>
<version>1.9.3</version>
</dependency>
Release Notes
Latest Release (2.1.1 - February 6, 2019)
- Introducing
SHUT_DOWN_STARTEDstate for theWorkerStateChangeListener. - Fixed a bug with
AWSSessionCredentialsusingAWSSecretIDinstead ofAWSAccessIDand vice versa. - Upgrading SDK version to 2.4.0, which includes a fix for a possible deadlock when using Enhanced Fan-Out.