Periodic blob sweep. Mirrors SnapshotWorker: unref'd timer, one sweep in
flight at a time, failures logged rather than thrown at the timer.
Every sweep logs a line, INCLUDING zero-delete sweeps. A GC that silently
stops running is the same defect class as the one that caused #2790, so the
healthy case has to be visible too, and failures increment a counter.
Periodic blob sweep. Mirrors
SnapshotWorker: unref'd timer, one sweep in flight at a time, failures logged rather than thrown at the timer.Every sweep logs a line, INCLUDING zero-delete sweeps. A GC that silently stops running is the same defect class as the one that caused #2790, so the healthy case has to be visible too, and failures increment a counter.