How to monitor resources used by scroll API for each scroll Id? what happens when clearScroll Api is called

Question

How to monitor memory resources or search contexts used by scroll API for each scroll Id? where does these search contexts are stored, is there a way to see or monitor them? wha

Answer 1

You can check how many search contexts are currently opened by calling the Node stats API but there's no way (that I know of) to see how much memory is used by them:

GET _nodes/stats/indices?filter_path=**.open_contexts

=>

{
  "nodes" : {
    "QjjWj45NQkGC9qcaylDDVQ" : {
      "indices" : {
        "search" : {
          "open_contexts" : 0
        }
      }
    },
    "eZbpkckXSxSxzD8c_QOkEA" : {
      "indices" : {
        "search" : {
          "open_contexts" : 3
        }
      }
    },
    "0VFJaC2uTraudPCMqODhiw" : {
      "indices" : {
        "search" : {
          "open_contexts" : 2
        }
      }
    }
  }
}

The search contexts are stored on the heap.

Furthermore, the keepAlive parameter tells how long the context stays available in memory before being cleared automatically.