Cloudera Docs

Configuring Dedicated Coordinators and Executors

Configure a dedicated coordinator and a dedicated executor roles to improve scalability of Impala.

Guidelines for Dedicated Coordinators and Executors

  • Dedicated coordinator:
    • Should be on an edge node with no other services running on it.
    • Does not need large local disks but still needs some that can be used for Spilling.
    • Require at least the same or even larger memory allocation than executors.
  • (Dedicated)Executors:
    • Should be co-located with DataNodes.
    • The number of hosts with dedicated executors typically increases as the cluster grows larger and handles more table partitions, data files, and concurrent queries.
  1. In Cloudera Manager, navigate to Clusters > Impala > Configuration > Role Groups.
  2. Click Create to create two role groups with the following values.
    1. Group for Coordinators
      1. Group Name: Coordinators
      2. Role Type: Impala Daemon
      3. Copy from:
        • Select Impala Daemon Default Group if you want the existing configuration gets carried over to the Coordinators.
        • Select None if you want to start with a blank configuration.
    2. Group for Executors
      1. Group Name: Executors
      2. Role Type: Impala Daemon
      3. Copy from:
        • Select Impala Daemon Default Group if you want the existing configuration gets carried over to the Executors.
        • Select None if you want to start with a blank configuration.
  3. In the Role Groups page, click Impala Daemon Default Group.
    1. Select the set of nodes intended to be coordinators.
      1. Click Action for Selected and select Move To Different Role Group….
      2. Select the Coordinators.
    2. Select the set of nodes intended to be Executors.
      1. Click Action for Selected and select Move To Different Role Group….
      2. Select the Executors.
  4. Click Configuration. In the search field, type Impala Daemon Specialization.
  5. Click Edit Individual Values.
  6. For Coordinators role group, select COORDINATOR_ONLY.
  7. For Executors role group, select EXECUTOR_ONLY.
  8. Click Save Changes and then restart the Impala service.