S3 Stream Upload

This library allows you to efficiently stream data to a location on AWS S3 in Java. The S3 API requires that a content length be set before starting uploading, which is a problem when you want to calculate a large amount of data on the fly. The standard Java AWS SDK will simply buffer all the data in memory so that it can calculate the length, which consumes RAM and delays the upload. You can write the data to a temporary file but disk IO is slow. This library provides an OutputStream that packages data written to it into chunks which are sent in a multipart upload. You can also use several streams and upload the data in parallel.

The entrypoint is the class StreamTransferManager. Read more in the javadoc, including a usage example.

This is available from maven central.

Changelog

2.2.1

Exceptions during upload lead to an exception in writers instead of them getting stuck trying to put on the queue.
Bump aws-java-sdk and slf4j-api dependency versions.

2.2.0

Add checkIntegrity() method thanks to @gkolakowski-ias. This allows verifying the upload with MD5 hashes.

2.1.0

Support uploading empty objects. In this case the user may want to override customisePutEmptyObjectRequest.
Bump aws-java-sdk and slf4j-api dependency versions.

2.0.3

Bump aws-java-sdk dependency version

2.0.2

Avoid race condition in big uploads causing some parts to be missing from final completed upload.

2.0.1

Allow thrown Errors (e.g. OOM) to bubble up unchanged.

2.0.0

The checkSize() method is now private as the user no longer needs to call it. You can remove all calls to it.
The constructor from version 1 is now deprecated. Instead you should call the 3 parameter constructor which has the essentials, and optionally chain the desired builder style setters to configure.