[CASSANDRA-19942] Pooled BTree.FastBuilder keeps references to data after reset

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Duplicate
• Fix Version/s: 4.0.x, 4.1.x, 5.0.x, 5.x
• Component/s: Local/Other
• Platform: All
• Assignee: Dmitry Konstantinov Assign to me
• Reporter: Dmitry Konstantinov

Authors

Dmitry Konstantinov

• Created: 22/Sep/24 12:52
• Updated: 22/Sep/24 13:30
• Resolved: 22/Sep/24 13:25

Description

Hi I am analyzing of argecolumn_test.TestLargeColumn test failure (CASSANDRA-19702) and have noticed that sometimes when I run the test locally it fails with OOM. The test sends an insert with a large column value.

In the created heap dump I have found that there is a kind of memory leaking for the sent column values though thread-local variable used for re-usable Pooled BTree.FastBuilder:

In normal cases it is probably not critical because the objects are not that huge but it is still a leak.

reset() logic in BTree.FastBuilder does not clean references to such values because during other operations like build() "count" value can be reset to 0.

 

Issue Links

• duplicates: CASSANDRA-19785 Possible memory leak in BTree.FastBuilder
• relates to: CASSANDRA-19702 Test failure: largecolumn_test.TestLargeColumn
• relates to: CASSANDRA-15510 BTree: Improve Building, Inserting and Transforming
• links to: GitHub Pull Request #3559