[KUDU-1414] Corrupting multiple log entries at the end of a WAL file may go undetected

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.8.0
• Component/s: log
• Code Review: http://gerrit.cloudera.org:8080/2763
• Assignee: Unassigned
• Reporter: Mike Percy
• Created: 12/Apr/16 01:42
• Updated: 21/Oct/16 18:13

Description

While looking at KUDU-1377, I investigated how we are handling WAL truncation when corruption is detected. The way the code is written today, a trailing series of corrupt log entries are truncated with only a log warning message. I'll post a unit test demonstrating this behavior.

One way to get around this is to ensure that we only accept zeros following a truncated record, instead of just bad records, in order to consider it a partially-written record that we can safely truncate. We would have to maintain this invariant when preallocating space and truncating partial records before continuing to write.