Hydra built-in support is available starting with IntelliJ IDEA 2017.3. This means you can benefit from Hydra parallel compilation within your preferred IDE independently of the build tool.
Upgrade or download the latest IntelliJ IDEA (minimum version 2017.3). Also, make sure to upgrade or install the IntelliJ IDEA Scala language support.
Restart IDEA when the update completed.
The Hydra settings panel is not visible by default. To make it visible, you have to open the Action dialog (press Ctrl+Shift+A on Windows/Linux or Cmd+Shift+A on Mac) and type "hydra".
Press enter on "Open Hydra Settings" and the Hydra Settings panel will open. From now on it will always be available under "Preferences > Build, Execution, Deployment > Compiler > Scala Compiler > Hydra Compiler".
Tick "Enable Hydra", provide your credentials, and set the version of Hydra you would like to use (any Hydra version after 0.9.7 will work). Click on the "Check connection" to validate the credentials are correct. Finally, after having set the Hydra version, click on the "Download" button. This will retrieve the required dependencies to compile your Scala project with Hydra.
Note Mind that Hydra needs to be explicitly enabled on each imported project.
Try to rebuild the project and check the "Messages" view
Keep in mind that the number of Hydra workers used may vary depending on your machine's hardware and the number of compiled sources.