Siren Federate User Guide

The cluster APIs enables the retrieval of cluster and node level information, such as statistics about off-heap memory allocation.

Nodes statistics

The cluster nodes stats API allows to retrieve one or more (or all) of the cluster nodes statistics.

GET /_siren/nodes/stats
GET /_siren/nodes/nodeId1,nodeId2/stats

The first command retrieves stats of all the nodes in the cluster. The second command selectively retrieves nodes stats of only nodeId1 and nodeId2.

By default, all stats are returned. You can limit this by combining any of the following stats:

Memory information

The memory flag can be set to retrieve information about the memory allocation:

GET /_siren/nodes/stats/memory

The response includes memory allocation statistics for each node as follows:

{
  "se6baEC9T4K7-14yuG2qgA": {
    "memory" : {
      "allocated_direct_memory_in_bytes" : 0,
      "allocated_root_memory_in_bytes": 0,
      "root_allocator_dump": "Allocator(ROOT) 0/0/3750232064/17179869184 (res/actual/peak/limit)"
    }
  },
  "sKnVUBo9ShGzkl4GYih7BA": {
    "memory" : {
      "allocated_direct_memory_in_bytes" : 0,
      "allocated_root_memory_in_bytes": 0,
      "root_allocator_dump": "Allocator(ROOT) 0/0/0/17179869184 (res/actual/peak/limit)"
    }
  }
}

Planner information

The planner flag can be set to retrieve information about the planner job and task pools:

GET /_siren/nodes/stats/planner

The response includes memory allocation statistics for each node as follows:

{
  "se6baEC9T4K7-14yuG2qgA": {
    "planner": {
      "thread_pool": {
        "job": {
          "permits": 1,
          "queue": 0,
          "active": 0,
          "largest": 1,
          "completed": 538
        },
        "task": {
          "permits": 3,
          "queue": 0,
          "active": 0,
          "largest": 3,
          "completed": 3955
        }
      }
    }
  },
  "sKnVUBo9ShGzkl4GYih7BA": {
    "planner": {
      "thread_pool": {
        "job": {
          "permits": 1,
          "queue": 0,
          "active": 0,
          "largest": 1,
          "completed": 537
        },
        "task": {
          "permits": 3,
          "queue": 0,
          "active": 0,
          "largest": 3,
          "completed": 3863
        }
      }
    }
  }
}

Optimizer statistics cache

The cluster optimizer cache API allows to retrieve a snapshot of the query optimizer cache for a list of the cluster nodes.

GET /_siren/cache
GET /_siren/nodeId1,nodeId2/cache
GET /_siren/cache/clear
GET /_siren/nodeId1,nodeId2/cache/clear

The first command retrieves the state of the optimizer cache for all the nodes in the cluster, while the second only for the desired list of node IDs. The third command invalidates the optimizer cache on every node, while the last command does so for only the selected nodes.

The response includes statistics about the cache use on each node:

{
  "aQAf0tIwRtq_n4mBr9SLTw": {
    "size": 92,
    "hit_count": 32,
    "miss_count": 92,
    "eviction_count": 42,
    "load_exception_count": 0,
    "load_success_count": 92,
    "total_load_time_in_millis": 68004
  }
}