I've been using matrix projects to perform multi-platform builds for some time. After upgrading to 1.570, the parent jobs for the matrix projects are consuming real executors (iow - they are not running as flyweight jobs) on my build boxes, which is causing deadlocks because the child jobs are waiting for free executors, while the parent is waiting for the child to complete. Very similar behavior to JENKINS-10944 . My build slaves are pretty much always online, so I don't think it's the same problem as described in JENKINS-22502. What additional information can I provide that might help track this down?