-
Type: Improvement
-
Resolution: Fixed
-
Priority: Major - P3
-
Affects Version/s: 6.0 Required, 7.0 Required, 8.0 Required
-
Component/s: None
-
Cluster Scalability
-
Fully Compatible
-
Cluster Scalability Priorities, Cluster Scalability 06/24/24, Cluster Scalability 2024-07-08
SessionCatalogMigrationSource::_fetchNextNewWriteOplog function can make recursive calls.
Consider the following case:
1. When oplog entries buffer is empty, it will fetch next oplog entry from the queue.
2. If this entry is ApplyOps from a transaction, it will unwrap it into several entries using SessionCatalogMigrationSource::_extractOplogEntriesForRetryableApplyOps
3. After unwrapping, it will make a recursive call. The assumption would be that because we just unwrapped a transaction, we should have an oplog entry in the buffer, so the recursion won't be deep.
4. However, when unwrapping, we are checking if modified documents are actually a part of the chunk we are migrating in SessionCatalogMigrationSource::shouldSkipOplogEntry.
5. So if the collection is getting a lot of write transactions, we might get a very deep recursive call, until we find a transaction that affects a migrated chunk.
This is not theoretical, there are stack traces that fill most of kStackTraceFrameMax with _fetchNextNewWriteOplog.
To avoid potential problem, I suggest re-writing this function to avoid recursion
- is duplicated by
-
SERVER-97458 Segmentation fault
- Closed
- is related to
-
SERVER-97458 Segmentation fault
- Closed