This reduces the number of goroutines and runtime timers when
ITIMER_VIRTUAL or ITIMER_PROF are enabled, or when RLIMIT_CPU is set.
This also ensures that thread group CPU timers only advance if running
tasks are observed at the time the CPU clock advances, mostly
eliminating the possibility that a CPU timer expiration observes no
running tasks and falls back to the group leader.
PiperOrigin-RevId: 217603396
Change-Id: Ia24ce934d5574334857d9afb5ad8ca0b6a6e65f4
Ian Gudger
Jamie Liu
Michael Pratt
Googler