.Slow progress and high CPU utilization during backfill is resolved Previously, the worker thread with the smallest index in an OSD shard would return to the main worker loop, instead of waiting until an item could be scheduled from the mClock queue or until notified. This resulted in the busy loop and high CPU utilization. With this fix, the worker thread with the smallest thread index reacquires the appropriate lock and waits until notified, or until time period lapses as indicated by the mClock scheduler. The worker thread now waits until an item can be scheduled from the mClock queue or until notified and then returns to the main worker loop thereby eliminating the busy loop and solving the high CPU utilization issue.