Merge Changes Summary

The Hazelcast and Hazelcast Jet products were merged together to provide a seamless experience. Changes done during the merge of Hazelcast and Hazelcast Jet codebases are summarized in this document.

Hazelcast Jet repository was merged into Hazelcast repository.

The name Jet doesn't refer to standalone product anymore, but is kept when referring to the streaming engine part of the product - the Jet engine.

Hazelcast repository - https://github.com/hazelcast/hazelcast Hazelcast Jet repository - https://github.com/hazelcast/hazelcast-jet

After some preparatory commits removing conflicting files (e.g. root pom.xml), the merge was performed by the following command:

$ git merge --allow-unrelated-histories hazelcast-jet/master

This preserves history for both projects and allows easy rebasing of patches both ways (forward porting and backporting from/to Hazelcast Jet).

Hazelcast repository continues its development as with a next major version.

Module changes

• hazelcast-jet-core code was merged into hazelcast module
• hazelcast-jet-spring module was merged into hazelcast-spring and removed
• hazelcast-jet-distribution module was removed, hazelcast-distribution module was adapted to produce very similar artifacts - full and slim distribution
• the extension modules were kept under extensions/*, keeping the groupId and artifactId coordinates, this makes it easy for existing users to migrate.
• examples modules were deleted, they will be merged with imdg example, which are stored in a separate repository at https://github.com/hazelcast/hazelcast-code-samples/
• hazelcast-jet-sql module was merged into hazelcast-sql module (this actually happened after the merge, but for users it is indistinguishable).`

Code Changes

• JetNodeExtension was merged with DefaultNodeExtension
• The Jet service is started when a HazelcastInstance is started
• HazelcastInstance can return JetInstance via #getJetInstance (this will change before the release into a JetService getJet() where JetService provides a subset of JetInstance methods)
• Jet data structures created by com.hazelcast.jet.impl.JobRepository are created lazily when needed
• JetConfig is now a field in com.hazelcast.config.Config
• Jet run tests in parallel by default, Jet tests were marked with QuickTest and ParallelJVMTest @Category accordingly
• IMDG's smallInstanceConfig() for tests sets the com.hazelcast.jet.config.InstanceConfig#setCooperativeThreadCount to 2
• Jet cooperative threads are suspended if no jobs are running.
• One can disable Jet code upload for security reasons.

Checkstyle

• Jet code was adapted to IMDG checkstyle rules
• some checkstyle rules were relaxed

There are 2 outstanding items to resolve:

• some checkstyle rules were ignored for Jet code
• Jet had some stricter rules regarding public javadoc, this is now not in place, ideally we should apply it to the whole product

Distribution

• IMDG and Jet distributions were merged, the result is closer to the Jet distribution as there were more features.
• the distribution is started using bin/hazelcast-start command
• the cli tool is under bin/hazelcast (used to be bin/jet)
• the configuration files
  • hazelcast.yaml - configuration file for hazelcast, contains also configuration for the Jet engine (follows the structure where the JetConfig is a field of Config)
  • hazelcast-client.yaml - configuration file for the CLI tool