* Introducing support for processing multiple kinesis data streams with the same KCL 2.x for java consumer application
* To build a consumer application that can process multiple streams at the same time, you must implement a new
interface called MultistreamTracker (https://github.com/awslabs/amazon-kinesis-client/blob/0c5042dadf794fe988438436252a5a8fe70b6b0b/amazon-kinesis-client/src/main/java/software/amazon/kinesis/processor/MultiStreamTracker.java)
* Behavior of shard synchronization is moving from each worker independently learning about all existing shards to workers only discovering the children of shards that each worker owns. This optimizes memory usage, lease table IOPS usage, and number of calls made to kinesis for streams with high shard counts and/or frequent resharding.
* When bootstrapping an empty lease table, KCL utilizes the `ListShard` API's filtering option (the ShardFilter optional request parameter) to retrieve and create leases only for a snapshot of shards open at the time specified by the `ShardFilter` parameter. The `ShardFilter` parameter enables you to filter out the response of the `ListShards` API, using the `Type` parameter. KCL uses the `Type` filter parameter and the following of its valid values to identify and return a snapshot of open shards that might require new leases.
* Currently, the following shard filters are supported:
*`AT_TRIM_HORIZON` - the response includes all the shards that were open at `TRIM_HORIZON`.
*`AT_LATEST` - the response includes only the currently open shards of the data stream.
*`AT_TIMESTAMP` - the response includes all shards whose start timestamp is less than or equal to the given timestamp and end timestamp is greater than or equal to the given timestamp or still open.
*`ShardFilter` is used when creating leases for an empty lease table to initialize leases for a snapshot of shards specified at `RetrievalConfig#initialPositionInStreamExtended`.
* For more information about ShardFilter, see the [official AWS documentation on ShardFilter](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_ShardFilter.html).
* Introducing support for the `ChildShards` response of the `GetRecords` and the `SubscribeToShard` APIs to perform lease/shard synchronization that happens at `SHARD_END` for closed shards, allowing a KCL worker to only create leases for the child shards of the shard it finished processing.
* For shared throughout consumer applications, this uses the `ChildShards` response of the `GetRecords` API. For dedicated throughput (enhanced fan-out) consumer applications, this uses the `ChildShards` response of the `SubscribeToShard` API.
* For more information, see the official AWS Documentation on [GetRecords](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetRecords.html), [SubscribeToShard](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_SubscribeToShard.html), and [ChildShard](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_ChildShard.html).
* KCL now also performs additional periodic shard/lease scans in order to identify any potential holes in the lease table to ensure the complete hash range of the stream is being processed and create leases for them if required. `PeriodicShardSyncManager` is the new component that is responsible for running periodic lease/shard scans.
* New configuration options are available to configure `PeriodicShardSyncManager` in `LeaseManagementConfig`
| leasesRecoveryAuditorExecutionFrequencyMillis | 120000 (2 minutes) | Frequency (in millis) of the auditor job to scan for partial leases in the lease table. If the auditor detects any hole in the leases for a stream, then it would trigger shard sync based on leasesRecoveryAuditorInconsistencyConfidenceThreshold. |
| leasesRecoveryAuditorInconsistencyConfidenceThreshold | 3 | Confidence threshold for the periodic auditor job to determine if leases for a stream in the lease table is inconsistent. If the auditor finds same set of inconsistencies consecutively for a stream for this many times, then it would trigger a shard sync |
* New CloudWatch metrics are also now emitted to monitor the health of `PeriodicShardSyncManager`:
| NumStreamsWithPartialLeases | Number of streams that had holes in their hash ranges. |
| NumStreamsToSync | Number of streams which underwent a full shard sync. |
* Introducing deferred lease cleanup. Leases will be deleted asynchronously by `LeaseCleanupManager` upon reaching `SHARD_END`, when a shard has either expired past the stream’s retention period or been closed as the result of a resharding operation.
* New configuration options are available to configure `LeaseCleanupManager`.
| leaseCleanupIntervalMillis | 1 minute | Interval at which to run lease cleanup thread. |
| completedLeaseCleanupIntervalMillis | 5 minutes | Interval at which to check if a lease is completed or not. |
| garbageLeaseCleanupIntervalMillis | 30 minutes | Interval at which to check if a lease is garbage (i.e trimmed past the stream's retention period) or not. |
* Introducing _experimental_ support for multistreaming, allowing a single KCL application to multiplex processing multiple streams.
* New configuration options are available to enable multistreaming in `RetrievalConfig#appStreamTracker`.
* Fixing a bug in `PrefetchRecordsPublisher` restarting while it was already running.
* Including an optimization to `HierarchicalShardSyncer` to only create leases for one layer of shards.
* Adding support to prepare and commit lease checkpoints with arbitrary bytes.
* This allows checkpointing of an arbitrary byte buffer up to the maximum permitted DynamoDB item size ([currently 400 KB as of release](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html)), and can be used for recovery by passing a serialized byte buffer to `RecordProcessorCheckpointer#prepareCheckpoint` and `RecordProcessorCheckpointer#checkpoint`.
* Upgrading version of AWS SDK to 2.14.0.
* [#725](https://github.com/awslabs/amazon-kinesis-client/pull/725) Allowing KCL to consider lease tables in `UPDATING` healthy.
* NOTE: SDK has a known connection teardown issue when multiple H2 streams are used within a connection. This might result in shard consumers sticking to a stale service host and not progressing. If your shard consumer gets stuck, use the following configuration as a workaround. This configuration might result in up to 5X increase in total connections.
* Introducing a validation step to verify if ShardEnd is reached, to prevent shard consumer stuck scenarios in the event of malformed response from service.
* Added timeouts on all futures returned from the DynamoDB and Kinesis clients.
The timeouts can be configured by setting `LeaseManagementConfig#requestTimeout(Duration)` for DynamoDB, and `PollingConfig#kinesisRequestTimeout(Duration)` for Kinesis.
`ReadTimeout` exceptions can occur if the client is unable to request data from Kinesis for more than client timeout, which defaults to 30 seconds. This can occur if the record processor blocks for more than the timeout period. `ReadTimeout` could also occur as part of [Issue #391](https://github.com/awslabs/amazon-kinesis-client/issues/391).
* Moved creation of `WorkerStateChangedListener` and `GracefulShutdownCoordinator` to the `CoordinatorConfig`.
Originally the `WorkerStateChangedListener` and `GracefulShutdownCoordinator` were created by methods on the `SchedulerCoordinatorFactory`, but they should have been configuration options.
The original methods have been deprecated, and may be removed at a later date.
* Added method `onAllInitializationAttemptsFailed(Throwable)` to `WorkerStateChangedListener` to report when all initialization attempts have failed.
This method is a default method, and it isn't require to implement the method. This method is only called after all attempts to initialize the `Scheduler` have failed.
* Fixed an issue where `ResourceNotFoundException` on subscription to a shard was not triggering end of shard handling.
If a lease table contains a shard that is no longer present in the stream attempt to subscribe to that shard will trigger a `ResourceNotFoundException`. These exception are treated the same as reaching the end of a shard.
* Fixed an issue where it was possible to get a duplicate record when resubscribing to a shard.
Subscribe to shard requires periodic resubscribing, and uses a new concept of a continuation sequence number. If the continuation sequence number was equal to the last record that record would be processed a second time. Resubscribing now uses `AFTER_SEQUENCE_NUMBER` to ensure that only later records are returned.
* Fixed an issue where time based restart of the subscription wasn't resetting the `lastRequestTime`.
If a subscription hasn't delivered any data for more than 30 seconds it will be canceled and restarted. This detection is based of the `lastRequestTime` which wasn't getting reset after the restart was triggered.
* Fixed an issue where requesting on the subscription from the `FanOutRecordsPublisher` could trigger an unexpected failure.
Due to a race condition the underlying flow in the subscription could be set to something else. The method is now synchronized, and verifies that the subscriber it was created with is still the subscriber in affect.
This issue generally would only appear when multiple errors were occurring while connecting to Kinesis.
* Fixed an issue where the number of requested items could exceed the capacity of the RxJava queue.
There was an off by one issue when determining whether to make a request to the SDK subscription. This changes the calculation to represent the capacity as a queue.
__WARNING: The Amazon Kinesis Client may see significantly increased latency, unless the `KinesisAsyncClient` is configured to have a `maxConcurrency` high enough to allow all leases plus additional usages of the `KinesisAsyncClient`.__
* The Amazon Kinesis Client now uses 3 additional Kinesis API's:
__WARNING: If using a restrictive Kinesis IAM policy you may need to add the following API methods to the policy.__
| consumerArn | Unset | The ARN for an already created consumer. If this is set, the Kinesis Client will not attempt to create a consumer. |
| streamName | Unset | The name of the stream that a consumer should be create for if necessary |
| consumerName | Unset | The name of the consumer to create. If this is not set the applicationName will be used instead. |
| applicationName | Unset | The name of the application. This is used as the name of the consumer unless consumerName is set. |
* Modular Configuration of the Kinesis Client
The Kinesis Client has migrated to a modular configuration system, and the `KinesisClientLibConfiguration` class has been removed.
Configuration has been split into 7 classes. Default versions of the configuration can be created from the `ConfigsBuilder`.
Please [see the migration guide for more information][migration-guide].
*`CheckpointConfig`
*`CoordinatorConfig`
*`LeaseManagementConfig`
*`LifecycleConfig`
*`MetricsConfig`
*`ProcessorConfig`
*`RetrievalConfig`
* Upgraded to AWS Java SDK 2.0
The Kinesis Client now uses the AWS Java SDK 2.0. The dependency on AWS Java SDK 1.11 has been removed.
All configurations will only accept 2.0 clients.
* When configuring the `KinesisAsyncClient` the `KinesisClientUtil#createKinesisAsyncClient` can be used to configure the Kinesis Client
* __If you need support for AWS Java SDK 1.11 you will need to add a direct dependency.__
__When adding a dependency you must ensure that the 1.11 versions of Jackson dependencies are excluded__
[Please see the migration guide for more information][migration-guide]
* MultiLangDaemon is now a separate module
The MultiLangDaemon has been separated to its own Maven module and is no longer available in `amazon-kinesis-client`. To include the MultiLangDaemon, add a dependency on `amazon-kinesis-client-multilang`.
* Introducing support for ListShards API. This API is used in place of DescribeStream API to provide more throughput during ShardSyncTask. Please consult the [AWS Documentation for ListShards](https://docs.aws.amazon.com/kinesis/latest/APIReference/API_ListShards.html) for more information.
* Added configuration parameters for ListShards usage
| Name | Default | Description |
| ---- | ------- | ----------- |
| [listShardsBackoffTimeInMillis](https://github.com/awslabs/amazon-kinesis-client/blob/3ae916c5fcdccd6b835c86ba7f6f53dd5b4c8b04/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1412) | 1500 ms | This is the default backoff time between 2 ListShards calls when throttled. |
| [listShardsRetryAttempts](https://github.com/awslabs/amazon-kinesis-client/blob/3ae916c5fcdccd6b835c86ba7f6f53dd5b4c8b04/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1423) | 50 | This is the maximum number of times the KinesisProxy will retry to make ListShards calls on being throttled. |
* Updating the version of AWS Java SDK to 1.11.272.
* Deprecated certain [KinesisProxy](https://github.com/awslabs/amazon-kinesis-client/blob/3ae916c5fcdccd6b835c86ba7f6f53dd5b4c8b04/src/main/java/com/amazonaws/services/kinesis/clientlibrary/proxies/KinesisProxy.java) constructors.
* Allow disabling check for the case where a child shard has an open parent shard.
There is a race condition where it's possible for the a parent shard to appear open, while having child shards. This check can now be disabled by setting [`ignoreUnexpectedChildShards`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1037) to true.
Logging long running tasks can be enabled by setting the following configuration property:
| Name | Default | Description |
| ---- | ------- | ----------- |
| [`logWarningForTaskAfterMillis`](https://github.com/awslabs/amazon-kinesis-client/blob/3de901ea9327370ed732af86c4d4999c8d99541c/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1367) | Not set | Milliseconds after which the logger will log a warning message for the long running task |
Added better handling of DynamoDB failures when updating leases. These failures would occur when a request to DynamoDB appeared to fail, but was actually successful.
Prefetching will retrieve and queue additional records from Kinesis while the application is processing existing records.
Prefetching can be enabled by setting [`dataFetchingStrategy`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1317) to `PREFETCH_CACHED`. Once enabled an additional fetching thread will be started to retrieve records from Kinesis. Retrieved records will be held in a queue until the application is ready to process them.
Pre-fetching supports the following configuration values:
| Name | Default | Description |
| ---- | ------- | ----------- |
| [`dataFetchingStrategy`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1317) | `DEFAULT` | Which data fetching strategy to use |
| [`maxPendingProcessRecordsInput`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1296) | 3 | The maximum number of process records input that can be queued |
| [`maxCacheByteSize`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1307) | 8 MiB | The maximum number of bytes that can be queued |
| [`maxRecordsCount`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1326) | 30,000 | The maximum number of records that can be queued |
| [`idleMillisBetweenCalls`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L1353) | 1,500 ms | The amount of time to wait between calls to Kinesis |
* Only advance the shard iterator for the accepted response.
This fixes a race condition in the `KinesisDataFetcher` when it's being used to make asynchronous requests. The shard iterator is now only advanced when the retriever calls `DataFetcherResult#accept()`.
* Call shutdown on the retriever when the record processor is being shutdown
This fixes a bug that could leak threads if using the [`AsynchronousGetRecordsRetrievalStrategy`](https://github.com/awslabs/amazon-kinesis-client/blob/9a82b6bd05b3c9c5f8581af007141fa6d5f0fc4e/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/AsynchronousGetRecordsRetrievalStrategy.java#L42) is being used.
The asynchronous retriever is only used when [`KinesisClientLibConfiguration#retryGetRecordsInSeconds`](https://github.com/awslabs/amazon-kinesis-client/blob/01d2688bc6e68fd3fe5cb698cb65299d67ac930d/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L227), and [`KinesisClientLibConfiguration#maxGetRecordsThreadPool`](https://github.com/awslabs/amazon-kinesis-client/blob/01d2688bc6e68fd3fe5cb698cb65299d67ac930d/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/KinesisClientLibConfiguration.java#L230) are set.
Applications can now set a pending checkpoint, before completing the checkpoint operation. Once the application has completed its checkpoint steps, the final checkpoint will clear the pending checkpoint.
Should the checkpoint fail the attempted sequence number is provided in the [`InitializationInput#getPendingCheckpointSequenceNumber`](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/types/InitializationInput.java#L81) otherwise the value will be null.
* Support timeouts, and retry for GetRecords calls.
Applications can now set timeouts for GetRecord calls to Kinesis. As part of setting the timeout, the application must also provide a thread pool size for concurrent requests.
When writes, or reads, to the lease table are throttled a warning will be emitted. If you're seeing this warning you should increase the IOPs for your lease table to prevent processing delays.
* Support configuring the graceful shutdown timeout for MultiLang Clients
This adds support for setting the timeout that the Java process will wait for the MutliLang client to complete graceful shutdown. The timeout can be configured by adding `shutdownGraceMillis` to the properties file set to the number of milliseconds to wait.
* Support timeouts for calls to the MultiLang Daemon
This adds support for setting a timeout when dispatching records to the client record processor. If the record processor doesn't respond within the timeout the parent Java process will be terminated. This is a temporary fix to handle cases where the KCL becomes blocked while waiting for a client record processor.
The timeout for the this can be set by adding `timeoutInSeconds = <timeout value>`. The default for this is no timeout.
__Setting this can cause the KCL to exit suddenly, before using this ensure that you have an automated restart for your application__
The MultiLangDaemon has been upgraded to use the v2 interfaces, which allows access to enhanced checkpointing, and more information during record processor initialization. The MultiLangDaemon clients must be updated before they can take advantage of these new features.
## Release 1.7.1 (November 3, 2016)
* General
* Allow disabling shard synchronization at startup.
* Applications can disable shard synchronization at startup. Disabling shard synchronization can application startup times for very large streams.
* Applications can now request a graceful shutdown, and record processors that implement the IShutdownNotificationAware will be given a chance to checkpoint before being shutdown.
* This adds a [new interface](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/interfaces/v2/IShutdownNotificationAware.java), and a [new method on Worker](https://github.com/awslabs/amazon-kinesis-client/blob/master/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java#L539).
* Add support for time based iterators ([See GetShardIterator Documentation](http://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetShardIterator.html))
The `KinesisClientLibconfiguration` now supports providing a `ShardPrioritization` strategy. This strategy controls how the `Worker` determines which `ShardConsumer` to call next. This can improve processing for streams that split often, such as DynamoDB Streams.
* Remove direct dependency on `aws-java-sdk-core`, to allow independent versioning.
* Artifacts are now signed by the identity `Amazon Kinesis Tools <amazon-kinesis-tools@amazon.com>`
## Release 1.6.3 (May 12, 2016)
* Fix format exception caused by DEBUG log in LeaseTaker [Issue # 68](https://github.com/awslabs/amazon-kinesis-client/issues/68)
## Release 1.6.2 (March 23, 2016)
* Support for specifying max leases per worker and max leases to steal at a time.
* Support for specifying initial DynamoDB table read and write capacity.
* Support for parallel lease renewal.
* Support for graceful worker shutdown.
* Change DefaultCWMetricsPublisher log level to debug. [PR # 49](https://github.com/awslabs/amazon-kinesis-client/pull/49)
* Avoid NPE in MLD record processor shutdown if record processor was not initialized. [Issue # 29](https://github.com/awslabs/amazon-kinesis-client/issues/29)
## Release 1.6.1 (September 23, 2015)
* Expose [approximateArrivalTimestamp](http://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetRecords.html) for Records in processRecords API call.
## Release 1.6.0 (July 31, 2015)
* Restores compatibility with [dynamodb-streams-kinesis-adapter](https://github.com/awslabs/dynamodb-streams-kinesis-adapter) (which was broken in 1.4.0).
## Release 1.5.1 (July 20, 2015)
* KCL maven artifact 1.5.0 does not work with JDK 7. This release addresses this issue.
* Support metrics level and dimension configurations to control CloudWatch metrics emitted by the KCL.
* Add new metrics that track time spent in record processor methods.
* Disable WorkerIdentifier dimension by default.
* **Exception Reporting** — Do not silently ignore exceptions in ShardConsumer.
* **AWS SDK Component Dependencies** — Depend only on AWS SDK components that are used.
## Release 1.4.0 (June 2, 2015)
* Integration with the **[Kinesis Producer Library (KPL)][kinesis-guide-kpl]**
* Automatically de-aggregate records put into the Kinesis stream using the KPL.
* Support checkpointing at the individual user record level when multiple user records are aggregated into one Kinesis record using the KPL.
See [Consumer De-aggregation with the KCL][kinesis-guide-consumer-deaggregation] for details.
## Release 1.3.0 (May 22, 2015)
* A new metric called "MillisBehindLatest", which tracks how far consumers are from real time, is now uploaded to CloudWatch.
## Release 1.2.1 (January 26, 2015)
* **MultiLangDaemon** — Changes to the MultiLangDaemon to make it easier to provide a custom worker.
## Release 1.2 (October 21, 2014)
* **Multi-Language Support** — Amazon KCL now supports implementing record processors in any language by communicating with the daemon over [STDIN and STDOUT][multi-lang-protocol]. Python developers can directly use the [Amazon Kinesis Client Library for Python][kclpy] to write their data processing applications.
## Release 1.1 (June 30, 2014)
* **Checkpointing at a specific sequence number** — The IRecordProcessorCheckpointer interface now supports checkpointing at a sequence number specified by the record processor.
* **Set region** — KinesisClientLibConfiguration now supports setting the region name to indicate the location of the Amazon Kinesis service. The Amazon DynamoDB table and Amazon CloudWatch metrics associated with your application will also use this region setting.
