If a disk or controller hardware is faulty then short-circuit read requests can stall indefinitely while reading from the file descriptor. Currently there is no way to detect when short-circuit read requests are slow or blocked.
This Jira proposes that each BlockReaderLocal maintain read statistics while it is active by measuring the time taken for a pre-determined fraction of read requests. These per-reader stats can be aggregated into global stats when the reader is closed. The aggregate statistics can be exposed via JMX.