Brief summary of changes:

• Cleaned up commented-out code
• Renamed _record_count to pending_record_count and _total_record_count to committed_record_count. The old properties are still callable but produce a deprecated warning. (If you were actually setting those values, you probably shouldn't have been doing that.)
• RecordWriterV1 now updates committed_record_count before clearing records. Previously it was the other way around, which seems like it would always produce incorrect data.