$ java PhaserPipeline

worker-0: finished round 1
worker-1: finished round 1
worker-2: finished round 1
worker-3: finished round 1
phaser onAdvance: phase 1 complete, 4 registered parties -> advancing
worker-4: registers after round 1 (phaser now has 5 parties)
worker-0: finished round 2
worker-1: finished round 2
worker-2: finished round 2
worker-3: finished round 2
worker-4: finished round 2
phaser onAdvance: phase 2 complete, 5 registered parties -> advancing
worker-0: finished round 3
worker-1: finished round 3
worker-2: finished round 3
worker-3: finished round 3
worker-4: finished round 3
phaser onAdvance: phase 3 complete, 5 registered parties -> advancing
done