1. Use Windows.
2. Open a console of any kind, in any Windows environment - cmd, powershell or the bash that ships with git.
3. Start a gradle task with an exec that never finishes.
4. Hit Ctrl+C or any preferred interrupt method.
5. Observe the process started by exec is not terminated.

Numerous people report issues related to this: #7603 #6114 #3093 #1128 #1109

I fixed this issue in NuProcess - brettwooldridge/NuProcess#133 - which you should use instead of ProcessBuilder on Windows. You will need to ping them to merge my PR.

You can trap Ctrl+C and use it to kill the subprocesses using NuProcess, or permit Ctrl+C to kill the daemon and using NuProcess, result in the child processes being terminated correctly.

Otherwise, Gradle is working really great for me.