[FLINK-10142] Reduce synchronization overhead for credit notifications

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.5.0, 1.5.1, 1.5.2, 1.5.3, 1.6.0, 1.7.0
• Fix Version/s: 1.5.4, 1.6.1, 1.7.0
• Component/s: Runtime / Network
• Labels: pull-request-available
• Assignee: Nico Kruber
• Reporter: Nico Kruber
• Created: 14/Aug/18 10:09
• Updated: 21/Nov/18 16:55
• Resolved: 21/Nov/18 16:55

Description

When credit-based flow control was introduced, we also added some checks and optimisations for uncommon code paths that make common code paths unnecessarily more expensive, e.g. checking whether a channel was released before forwarding a credit notification to Netty. Such checks would have to be confirmed by the Netty thread anyway and thus only add additional load for something that happens only once (per channel).

Issue Links

• depends upon: FLINK-10141 Reduce lock contention introduced with 1.5
• links to: GitHub Pull Request #6555