[FLINK-6565] Improve error messages for state restore failures

• Type: Improvement
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.3.0
• Fix Version/s: 1.3.0, 1.4.0
• Component/s: Runtime / State Backends
• Assignee: Tzu-Li (Gordon) Tai
• Reporter: Tzu-Li (Gordon) Tai
• Created: 12/May/17 08:08
• Updated: 13/May/17 09:10
• Resolved: 13/May/17 09:09

Description

The error messages thrown when state restore fails needs to be more explicit and clear of the actual reason.

At least 2 cases we've seen so far:

1.
For example, currently, when restoring an operator state or memory-backed keyed state, the previous serializer must exist. If it doesn't exist, currently only a vague NPE is thrown, without a clear message of the actual reason.

2.
If the restore failure was due to an incompatible version of a serializer's config snapshot, then it should report something more informative then: "Incompatible version: found 1, required 1."

Issue Links

• links to: GitHub Pull Request #3882