The "per project" throttling is broken for matrix jobs.

For testing, I've created a 96 element (12x8) matrix job. It's attached as CCI_Adm_Darrel_play_Matrix.xml.

Control Attempt

With no throttling, the quantity of concurrent child builds is limited only by my available executors.

Attempt #1

Throttling thusly:

• this project alone – radio button SELECTED
• max total builds – 7
• max builds per node – 0 (infinite)
• matrix master builds – check ON
• matrix config builds – check ON

RESULT Failure! No throttling happens.

Attempt #2

Throttling thusly:

• this project alone – radio button SELECTED
• max total builds – 7
• max builds per node – 0 (infinite)
• matrix master builds – check OFF
• matrix config builds – check ON

RESULT Failure! No throttling happens.

Success via "category" throttling

Throttling thusly:

• System Config
  • "Manage Jenkins" > "Configure System" > (heading) "Throttle Concurrent Builds"
  • category name = darrel_play_matrix
  • max total builds = 7
  • max per node = 0
• Job Config
  • throttle as part of categorie(s) – radio button SELECTED
  • max total builds = 7 (I expect this to be ignored)
  • max config builds = 7 (I expect this to be ignored)
  • multi-project category = "darrel_play_matrix" check ON
  • matrix master builds – check OFF
  • matrix config builds – check ON

RESULT Success! This behaves exactly like I expect it to.

However, my (strong) preference is to use "per project" throttling, so I don't have to create global throttling categories for 100s of developers.