why ansible inventory parser my json so slow

Question

I generate a json from public cloud but ansible use this inventory.json so slow. pls tell me why my json like this:

{
  "angelbeats": {
    "hosts": ["10.193.0.24", "10.193.0.23"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "grammy": {
    "hosts": ["10.193.2.5", "10.193.0.9", "10.193.10.4", "10.193.8.5"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "cdn": {
    "hosts": ["10.193.0.12", "10.193.0.11", "10.193.2.7", "10.193.2.8"],
    "vars": {
      "ansible_ssh_user": "root"
    }
  },
  "mdianying": {
    "hosts": ["10.193.0.31"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "zkmq": {
    "hosts": ["10.193.0.26", "10.193.0.27", "10.193.0.25"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "bmovie": {
    "hosts": [],
    "children": ["angelbeats", "growingpains", "forrestgump", "zkmq", "job", "tm", "inception"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "xxljob": {
    "hosts": ["10.193.0.6"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "redis": {
    "hosts": ["10.193.0.40", "10.193.2.13"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "tm": {
    "hosts": ["10.193.0.13", "10.193.0.14", "10.193.0.16", "10.193.0.17", "10.193.0.15"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "dns": {
    "hosts": ["10.193.0.100", "10.193.2.100", "10.193.10.10", "10.193.8.19"],
    "vars": {
      "ansible_ssh_user": "root"
    }
  },
  "yctask": {
    "hosts": ["10.193.8.15"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "cmovie": {
    "hosts": [],
    "children": ["angelbeats", "growingpains", "forrestgump", "zkmq", "job", "tm", "inception"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "forrestgump": {
    "hosts": ["10.193.0.104", "10.193.2.101", "10.193.8.20", "10.193.10.11"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "pwapi": {
    "hosts": ["10.193.0.28", "10.193.2.11", "10.193.8.10", "10.193.10.9"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "pwweb": {
    "hosts": ["10.193.0.20", "10.193.0.19", "10.193.2.9", "10.193.2.10", "10.193.8.9", "10.193.8.8", "10.193.10.6", "10.193.10.7"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "pwtask": {
    "hosts": ["10.193.0.29"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "apishow": {
    "hosts": ["10.193.0.32", "10.193.8.11"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "inception": {
    "hosts": ["10.193.0.10", "10.193.2.6", "10.193.8.7", "10.193.10.5"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "moviebi": {
    "hosts": ["10.193.0.42", "10.193.8.18"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "yanchu": {
    "hosts": ["10.193.0.35", "10.193.8.14"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "growingpains": {
    "hosts": ["10.193.0.21", "10.193.0.22"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "goods": {
    "hosts": ["10.193.0.33", "10.193.8.12"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "urm": {
    "hosts": ["10.193.0.39", "10.193.2.12"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "job": {
    "hosts": ["10.193.0.105"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  },
  "order": {
    "hosts": ["10.193.0.34", "10.193.8.13"],
    "vars": {
      "ansible_ssh_user": "wangluoli"
    }
  }
}

Answer 1

You need to create a _meta section in your JSON:

https://docs.ansible.com/ansible/latest/dev_guide/developing_inventory.html#tuning-the-external-inventory-script

The stock inventory script system detailed above works for all versions of Ansible, but calling --host for every host can be rather inefficient, especially if it involves API calls to a remote subsystem.

To avoid this inefficiency, if the inventory script returns a top level element called “_meta”, it is possible to return all of the host variables in one script execution. When this meta element contains a value for “hostvars”, the inventory script will not be invoked with --host for each host. This results in a significant performance increase for large numbers of hosts.