When distcp handles small files (file size slightly smaller than bandwidth), the throttler only starts to throttle after 1 second, and the throttled is specific to a single file, causing distcp to fill the cluster bandwidth and crush production traffic. This is a workload scale bug that manifests when processing many small files.

Root Cause: The ThrottledInputStream class has a bug in getBytesPerSec() method where division by zero or very small elapsed time results in incorrect throttling calculations for small files.