Creating a Resource Pool

Background

openGauss creates resource pools to divide host resources. After resource load management is enabled, the default resource pool alone is insufficient to address the resource load management requirements of services. Therefore, new resource pools must be used to reallocate system resources for granular control purposes. Table 1 describes the features of a common resource pool.

Table 1 Features of a common resource pool

Resource Pool

Feature

Common resource pool (common scenario)

  • A common resource pool is associated with a Workload Cgroup, and its group resource pool must not be associated with the corresponding sub-Class Cgroup. For example, to create a service resource pool and associate it with class1:wd, ensure that its group resource pool has not been associated with class1.
  • The default value of mem_percent is 0%. The sum of mem_percent for all common resource groups under the same group resource pool can be greater than or equal to 100%.

After resource load management is enabled, the system automatically creates default_pool. If no resource pool is specified for a session or user, they will be automatically associated with default_pool. By default, default_pool is associated with the DefaultClass:Medium Cgroup and does not limit the number of concurrent services. Table 2 describes the attributes of default_pool.

Table 2 default_pool attributes

Attribute

Value

Description

respool_name

default_pool

Name of the resource pool

mem_percent

100

Maximum percentage of used memory

cpu_affinity

–1

CPU affinity (reserved)

control_group

DefaultClass:Medium

Cgroup associated with the resource pool

active_statements

–1

Maximum number of concurrent queries allowed by the resource pool. The value –1 indicates that the number of concurrent queries is not limited.

max_dop

1

Concurrency level of execution operators after the SMP is enabled (reserved)

memory_limit

8GB

Upper memory usage limit (reserved)

parentid

0

OID of the parent resource pool

io_limits

0

Upper limit of IOPS. It is counted by ones for column storage and by 10 thousands for row storage. The value 0 indicates there is no limit.

io_priority

None

I/O priority set for jobs that consume many I/O resources. It takes effect when the I/O usage reaches 90%. None indicates there is no control.

nodegroup

installation

Name of the logical cluster to which the resource pool belongs

is_foreign

f

Specifies that the resource pool is not used for users outside the logical cluster.

NOTICE:

default_pool cannot be modified in openGauss.

Prerequisites

You are familiar with the CREATE RESOURCE POOL, ALTER RESOURCE POOL, and DROP RESOURCE POOLsyntax.

Procedure

Creating a resource pool

  1. Perform the steps in Using gsql to Connect to a Database.

  2. Create a group resource pool and associate it with the specified sub-Class Cgroup. In the following example, the group resource pool named resource_pool_a is associated with the class_a Cgroup.

    openGauss=# CREATE RESOURCE POOL resource_pool_a WITH (control_group='class_a');
    openGauss=# CREATE RESOURCE POOL resource_pool_b WITH (control_group='class_b');
    CREATE RESOURCE POOL
    
  3. Create a service resource pool and associate it with the specified Workload Cgroup. In the following example, the service resource pool named resource_pool_a1 is associated with the workload_a1 Cgroup.

    openGauss=# CREATE RESOURCE POOL resource_pool_a1 WITH (control_group='class_a:workload_a1');
    openGauss=# CREATE RESOURCE POOL resource_pool_a2 WITH (control_group='class_a:workload_a2');
    openGauss=# CREATE RESOURCE POOL resource_pool_b1 WITH (control_group='class_b:workload_b1');
    openGauss=# CREATE RESOURCE POOL resource_pool_b2 WITH (control_group='class_b:workload_b2');
    CREATE RESOURCE POOL
    

    NOTE:

    • If you do not specify an associated Cgroup when creating a resource pool, the resource pool will be associated with the default Cgroup, which is the Timeshare Cgroup Medium under the DefaultClass Cgroup.
    • The value of control_group is case-sensitive and must be contained in single quotation marks ('').
    • If a database user specifies the Timeshare string (Rush, High, Medium, or Low) in the syntax, for example, control_group is set to High, the resource pool will be associated with the High Timeshare Cgroup under DefaultClass.
    • control_group allows you to create a Workload Cgroup, for example, class1:wd whose Cgroup level can also be appended, such as class1:wd:2. The Cgroup level must be within 1 to 10, but it is not used for Cgroup differentiation. In earlier versions, you can create Workload Cgroups with the same name and differentiate them by their levels. In the latest version, Cgroup names must be unique. If you have created duplicate Workload Cgroups in an earlier version, delete them to avoid confusion.

Managing resource pools

Modify resource pool attributes. In the following example, the Cgroup associated with the resource pool resource_pool_a2 is changed to class_a:workload_a1 (assuming that class_a:workload_a1 is not associated with any other resource pools).

openGauss=# ALTER RESOURCE POOL resource_pool_a2 WITH (control_group="class_a:workload_a1");
ALTER RESOURCE POOL

Deleting a resource pool

Delete a resource pool. For example, run the following command to delete the resource pool resource_pool_a2:

openGauss=# DROP RESOURCE POOL resource_pool_a2;
DROP RESOURCE POOL

NOTE:

  • The resource pool cannot be deleted if it is associated with a role.
  • In a multi-tenant scenario, deleting a group resource pool also deletes the related service resource pools. A resource pool can be deleted only when it is not associated with any users.

Viewing Resource Pool Information

NOTICE:

  • Do not use the INSERT, UPDATE, DELETE, and TRUNCATE statements in the pg_resource_pool system catalog that manages resource load.
  • Do not modify the memory_limit and cpu_affinity attributes of a resource pool.
  • Run the following command to view the information of all the resource pools of the current cluster:

    openGauss=# SELECT * FROM PG_RESOURCE_POOL;
    
       respool_name   | mem_percent | cpu_affinity |    control_group    | active_statements | max_dop | memory_limit | parentid | io_limits | io_priority |  nodegroup   | is_foreign  | max_worker
    ------------------+-------------+--------------+---------------------+-------------------+---------+--------------+----------+-----------+--------------+--------------+------------
     default_pool     |         100 |           -1 | DefaultClass:Medium |                -1 |       1 | 8GB          |        0 |         0 | None        | installation | f  |
     resource_pool_a  |          20 |           -1 | class_a             |                10 |       1 | 8GB          |        0 |         0 | None        | installation | f  |
     resource_pool_b  |          20 |           -1 | class_b             |                10 |       1 | 8GB          |        0 |         0 | None        | installation | f  |
     resource_pool_a1 |          20 |           -1 | class_a:workload_a1 |                10 |       1 | 8GB          |    16970 |         0 | None        | installation | f  |
     resource_pool_a2 |          20 |           -1 | class_a:workload_a2 |                10 |       1 | 8GB          |    16970 |         0 | None        | installation | f  |
     resource_pool_b1 |          20 |           -1 | class_b:workload_b1 |                10 |       1 | 8GB          |    16971 |         0 | None        | installation | f  |
     resource_pool_b2 |          20 |           -1 | class_b:workload_b2 |                10 |       1 | 8GB          |    16971 |         0 | None        | installation | f  |
    (7 rows)
    
  • View information about Cgroups associated with a resource pool. For details, see gs_control_group_info(p….

    In the following example, resource_pool_a1 is the name of the resource pool.

    openGauss=# SELECT * FROM gs_control_group_info('resource_pool_a1');
    
            name         |  class  |  workload   | type  | gid | shares | limits | rate | cpucores
    ---------------------+---------+-------------+-------+-----+--------+--------+------+----------
     class_a:workload_a1 | class_a | workload_a1 | DEFWD |  87 |     30 |      0 |    0 | 0-3
    (1 row)
    

    Table 3 gs_control_group_info attributes

    Attribute

    Value

    Description

    name

    class_a:workload_a1

    Class name and workload name

    class

    class_a

    Class Cgroup name

    workload

    workload_a1

    Workload Cgroup name

    type

    DEFWD

    Cgroup type (Top, CLASS, BAKWD, DEFWD, and TSWD)

    gid

    87

    Cgroup ID

    shares

    30

    Percentage of CPU resources to those on the parent node

    limits

    0

    Percentage of CPU cores to those on the parent node

    rate

    0

    Allocation ratio in Timeshare

    cpucores

    0-3

    CPU cores

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    openGauss 2024-07-19 01:03:13
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