[FLINK-10082] Initialize StringBuilder in Slf4jReporter with estimated size

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.5.2, 1.6.0
• Fix Version/s: 1.5.4, 1.6.1, 1.7.0
• Component/s: Runtime / Metrics
• Labels: pull-request-available
• Assignee: Chesnay Schepler
• Reporter: Chesnay Schepler
• Created: 07/Aug/18 08:30
• Updated: 20/Aug/18 15:43
• Resolved: 20/Aug/18 15:43

Description

The Slf4jReporter uses a StringBuilder to generate the report that is later logged. Currently we don't pass the initial size, which for large deployments can result in frequent resizing of the backing array.

We could either estimate the expected size based on the # of metrics, or store the size of the last report (given that the total metrics space is fairly constant).

Issue Links

• links to: GitHub Pull Request #6580