According to the Document, the backpressure monitor only triggered on request and it is currently not available via metrics. This means that in the web UI we have no way to show all the backpressure state of all vertexes at the same time. The users need to click every vertex to get its backpressure state.
In Flink 1.9.0 and above, there are four metrics available(outPoolUsage, inPoolUsage, floatingBuffersUsage, exclusiveBuffersUsage), we can use these metrics to determine if there are possible backpressure, and then use the backpressure REST API to confirm it.
Here is a table get from https://flink.apache.org/2019/07/23/flink-network-stack-2.html
We can display the possible backpressure status on the vertex graph, thus users can get all the vertex backpressure states and locate the potential problem quickly.
REST API needed:
add outPoolUsage, inPoolUsage, floatingBuffersUsage, exclusiveBuffersUsage metrics for each vertex in the /jobs/:jobId API