[FLINK-23321] Make JM REST Netty thread pool count configurable

• Type: Improvement
• Status: Open
• Priority: Not a Priority
• Resolution: Unresolved
• Component/s: Runtime / Metrics, Runtime / REST
• Labels: Monitoring Netty REST auto-deprioritized-minor
• Flags: Patch
• Assignee: Unassigned
• Reporter: Nicolas Raga
• Created: 09/Jul/21 00:45
• Updated: 04/Feb/22 10:36

Description

Currently rest.server.numThreads works to create more DispatcherRestEndpoint threads which help in high usage of functionality in the purview of job the dispatcher functionality. However, we cannot tune the number of netty threads use to handle requests. Especially when using the REST server as a monitoring endpoint, a lack of netty threads when processing of AbstractHandlers takes a long causes extended response times. 

Such configuration already exists for taskmanagers (taskmanager.network.netty.client/server.numThreads) and such implementation of a server.netty-boss.numThreads and server.netty-worker.numThreads would be of great use.