[FLINK-10141] Reduce lock contention introduced with 1.5

• Type: Bug
• 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 09:50
• Updated: 30/Aug/18 21:07
• Resolved: 30/Aug/18 21:07

Description

With the changes around introducing credit-based flow control as well as the low latency changes, unfortunately, we also introduced some lock contention on RemoteInputChannel#bufferQueue and RemoteInputChannel#receivedBuffers as well as asking for queue sizes when the only thing we need is whether it is empty or not.

This was observed as a high idle CPU load with no events in the stream but only watermarks (every 500ms) and many slots on a single machine.

Issue Links

• is depended upon by: FLINK-10142 Reduce synchronization overhead for credit notifications
• links to: GitHub Pull Request #6553