Adjusting Scaling Policies for Queues in an Elastic Resource Pool

Precautions

• You are advised to implement fine-grained management of resource pools for stream and batch processing jobs by placing Flink real-time stream jobs and SQL batch processing jobs in separate elastic resource pools.

  Flink real-time stream jobs can run stably without forced scale-in, thus avoiding job interruption and system instability.

  SQL batch processing jobs are placed in independent resource pools, which can scale out and in more flexibly, significantly enhancing the success rate and operational efficiency of scaling operations.

• In any time segment of a day, the total minimum CUs of all queues in an elastic resource pool cannot be more than the minimum CUs of the pool.
• In any time segment of a day, the maximum CUs of any queue in an elastic resource pool cannot be more than the maximum CUs of the pool.
• The periods of scaling policies cannot overlap.
• The period of a scaling policy can only be set by hour and specified by the start time and end time. For example, if you set the period to 00-09, the time range when the policy takes effect is [00:00, 09:00). The period of the default scaling policy cannot be modified.
• In any period, compute resources are preferentially allocated to meet the minimum number of CUs of all queues. The remaining CUs (total CUs of the elastic resource pool – total minimum CUs of all queues) are allocated in accordance with the scaling policy priorities.
• After the queue is scaled out, the system starts billing you for the added CUs. So, if you do not have sufficient requirements, scale in your queue to release unnecessary CUs to save cost.

  Table 1 CU allocation (without jobs)

  Scenario	CUs
  An elastic resource pool has a maximum number of 256 CUs for queue A and queue B. The scaling policies are as follows: Queue A: priority 5; period: 00:00–09:00; minimum CU: 32; maximum CU: 64 Queue B: priority 10; time period: 00:00–09:00; minimum CU: 64; maximum CU: 128	From 00:00 a.m. to 09:00 a.m.: The minimum CUs are allocated to the two queues. Queue A has 32 CUs, and queue B has 64 CUs. There are 160 CUs remaining. The remaining CUs are allocated based on priority. Since queue B has a higher priority than queue A, 64 CUs will be allocated to queue B first, followed by the allocation of 32 CUs to queue A.
  An elastic resource pool has a maximum number of 96 CUs for queue A and queue B. The scaling policies are as follows: Queue A: priority 5; period: 00:00–09:00; minimum CU: 32; maximum CU: 64 Queue B: priority 10; time period: 00:00–09:00; minimum CU: 64; maximum CU: 128	From 00:00 a.m. to 09:00 a.m.: The minimum CUs are allocated to the two queues. Queue A has 32 CUs, and queue B has 64 CUs. There are no remaining CUs. The allocation is complete.
  An elastic resource pool has a maximum number of 128 CUs for queue A and queue B. The scaling policies are as follows: Queue A: priority 5; period: 00:00–09:00; minimum CU: 32; maximum CU: 64 Queue B: priority 10; time period: 00:00–09:00; minimum CU: 64; maximum CU: 128	From 00:00 a.m. to 09:00 a.m.: The minimum CUs are allocated to the two queues. Queue A has 32 CUs, and queue B has 64 CUs. There are 32 CUs remaining. The remaining 32 CUs are preferentially allocated to queue B.
  An elastic resource pool has a maximum number of 128 CUs for queue A and queue B. The scaling policies are as follows: Queue A: priority 5; period: 00:00–09:00; minimum CU: 32; maximum CU: 64 Queue B: priority 5; time period: 00:00–09:00; minimum CU: 64; maximum CU: 128	From 00:00 a.m. to 09:00 a.m.: The minimum CUs are allocated to the two queues. Queue A has 32 CUs, and queue B has 64 CUs. There are 32 CUs remaining. The two queues have the same priority, the remaining 32 CUs are randomly allocated to the two queues.

  Table 2 CU allocation (with jobs)

  Scenario	Actual CUs of Elastic Resource Pool	CUs Allocated to Queue A	CUs Allocated to Queue B	Allocation Description
  Queues A and B are added to the elastic resource pool. The scaling policies are as follows: Queue A: period: 00:00–09:00; minimum CU: 32; maximum CU: 64 Queue B: period: 00:00–09:00; minimum CU: 64; maximum CU: 128	192 CUs	64 CUs	128 CUs	If the actual CUs of the elastic resource pool are greater than or equal to the sum of the maximum CUs of the two queues, the maximum CUs are allocated to both queues.
  	96 CUs	32 CUs	64 CUs	The elastic resource pool preferentially meets the minimum CUs of the two queues. After the minimum CUs are allocated to the two queues, no CUs are allocatable.
  	128 CUs	32 CUs to 64 CUs	64 CUs to 96 CUs	The elastic resource pool preferentially meets the minimum CUs of the two queues. That is, 32 CUs are allocated to queue A, 64 CUs are allocated to queue B, and the remaining 32 CUs are available. The remaining CUs are allocated based on the queue load and priority. The actual CUs of the queue change within the range listed.

Managing Queues

1. In the navigation pane on the left, choose Resources > Resource Pool.
2. Locate the target elastic resource pool and click Queue MGMT in the Operation column. The Queue Management page is displayed.
3. View the queues added to the elastic resource pool.

   Table 3 Queue parameters

   Parameter	Description
   Name	Name of the queue to add
   Type	Queue type For SQL For general purpose
   Period	The start and end time of the queue scaling policy. This time range includes the start time but not the end time, that is, [start time, end time).
   Min CUs	Minimum number of CUs allowed by the scaling policy.
   Max CUs	Maximum number of CUs allowed by the scaling policy.
   Priority	Priority of the scaling policy for a queue in the elastic resource pool. The priority ranges from 1 to 100. A smaller value indicates a lower priority.
   Engine	For a queue running SQL jobs, the engine is Spark. For a queue for general purpose, the engine can be Spark or Flink, but it is displayed by -- in this page.
   Created	Time when a queue is added to the elastic resource pool
   Enterprise Project	Enterprise project the queue belongs to. Queues under different enterprise projects can be added to an elastic resource pool.
   Owner	User who added this queue
   Operation	Edit: Modify or add a scaling policy. Delete: Delete the queue.

   Figure 1 Managing queues
   

4. Locate the target queue and click Edit in the Operation column.
5. In the displayed Queue Management pane, perform the following operations as needed:
   Figure 2 Editing scaling policies for a queue
   
   • Add: Click Create to add a scaling policy. Set Priority, Period, Min CU, and Max CU, and click OK.
   • Modify: Modify parameters of an existing scaling policy and click OK.
   • Delete: Locate the row that contains the scaling policy you want, click Delete and click OK.
     

     The Priority and Period parameters must meet the following requirements:

     • Priority: The default value is 1. The value ranges from 1 to 100. A larger value indicates a higher priority.
     • Period:
       • You can only set the period to hours in [start time,end time) format.
       • For example, if the Period to 01 and 17, the scaling policy takes effect at 01:00 a.m. till 05:00 p.m.
       • The periods of scaling policies with different priorities cannot overlap.
     • Max CUs and Min CUs:
       • In any time segment of a day, the total minimum CUs of all queues in an elastic resource pool cannot be more than the minimum CUs of the pool.
       • In any time segment of a day, the maximum CUs of any queue in an elastic resource pool cannot be more than the maximum CUs of the pool.

6. After you finish the settings, click statistics icon in the upper right corner of the queue list to view all scaling policies of all queue in the elastic resource pool.
   Figure 3 Viewing statistic graphics
   
   Figure 4 Statistic graphics of queues and scaling policies
   

7. View the scaling task generated when the scaling starts. Go to Job Management > SQL Jobs and view the jobs of the SCALE_QUEUE type.