[CASSANDRA-3085] Race condition in sstable reference counting

• Type: Bug
• Status: Resolved
• Priority: Urgent
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Severity: Critical
• Assignee: Jonathan Ellis
• Reporter: Jonathan Ellis

Authors

Jonathan Ellis

Reviewers

Sylvain Lebresne

• Created: 26/Aug/11 19:22
• Updated: 16/Apr/19 09:32
• Resolved: 29/Aug/11 20:29

Description

DataTracker gives us an atomic View of memtable/sstables, but acquiring references is not atomic. So it is possible to acquire references to an SSTableReader object that is no longer valid, as in this example:

View V contains sstables

{A, B}

. We attempt a read in thread T using this View.
Meanwhile, A and B are compacted to

{C}

, yielding View W. No references exist to A or B so they are cleaned up.
Back in thread T we acquire references to A and B. This does not cause an error, but it will when we attempt to read from them next.