[FLINK-15021] Remove the setting of netty channel watermark in NettyServer

• Type: Sub-task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.11.0
• Component/s: Runtime / Network
• Labels: pull-request-available
• Assignee: Zhijiang
• Reporter: Zhijiang
• Created: 03/Dec/19 03:09
• Updated: 07/Jan/20 02:32
• Resolved: 07/Jan/20 02:21

Description

The high and low watermark setting in NetterServer before was mainly used for network flow control and limiting the maximum memory overhead caused by copying data inside netty stack. In detail, when the downstream side processes slowly and exhausted the available buffers finally, it would temporarily close the auto read switch in netty stack. Then the upstream side would finally reach the high watermark of channel to become unwritable.

But based on credit-based flow control and reusing flink network buffer inside netty stack, the watermark setting is not invalid now. So we can safely remove it to cleanup the codes.

Issue Links

• links to: GitHub Pull Request #10617