[KAFKA-4429] records-lag should be zero if FetchResponse is empty

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.10.2.0
• Assignee: Dong Lin
• Reporter: Dong Lin
• Created: 22/Nov/16 00:23
• Updated: 03/Jan/17 22:12
• Resolved: 03/Jan/17 22:11

Description

In Fetcher we record records-lag in terms of number of records for any partition. Currently this metric value is updated only if number of parsed records is not empty. This means that if consumer has already fully caught up and there is no new data into the topic, this metric's value will be negative infinity and users can not rely on this metric to know if their consumer has caught up.

We can fix this problem by assuming the lag is zero is FetchResponse is empty.

Issue Links

• relates to: KAFKA-3241 JmxReporter produces invalid JSON when a value is Infinity
• links to: GitHub Pull Request #2155