[IGNITE-12739] Optimistic serializable transactions may fail infinitely when read-through is enabled

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.8
• Fix Version/s: 2.9
• Assignee: Vladimir Steshin
• Reporter: Alexey Goncharuk
• Created: 03/Mar/20 09:19
• Updated: 13/Apr/20 07:26
• Resolved: 13/Apr/20 07:26

Description

In current design it is possible that the same key-value pair will be stored with different versions on primary and backup nodes. For example, a read-through is invoked separately on primary backup and values are stored with node local version.

With this precondition, if an optimistic serializable transaction is started from a backup node, the serializable check version is read from backup, but validated on primary node, which will fail the transaction with optimistic read/write conflict exception until the versions are overwritten to the same value (for example, via a pessimistic transaction).

While we need to additionally investigate whether we want to change the read-through logic to ensure the same value and version on all nodes, this particular scenario should be fixed by always enforcing reading from a primary node inside an optimistic serializable transaction.

The reproducer is attached. A known workaround is to disable read load balancing by setting "-DIGNITE_READ_LOAD_BALANCING=false" system property.

Issue Links

• links to: GitHub Pull Request #7575