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Scheduled Task

job_queue_processes

Parameter description: Specifies the number of jobs that can be concurrently executed. This parameter is a POSTMASTER parameter. You can set it using gs_guc, and you need to restart gaussdb to make the setting take effect.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: 0 to 1000

Function:

  • Setting job_queue_processes to 0 indicates that the scheduled job function is disabled and that no job will be executed. (Enabling scheduled jobs may affect the system performance. At sites where this function is not required, you are advised to disable it.)
  • Setting job_queue_processes to a value that is greater than 0 indicates that the scheduled job function is enabled and this value is the maximum number of jobs that can be concurrently processed.

After the scheduled job function is enabled, the job_scheduler thread polls the pg_job system catalog at a scheduled interval. The scheduled job check is performed every second by default.

Too many concurrent jobs consume many system resources, so you need to set the number of concurrent jobs to be processed. If the current number of concurrent jobs reaches the value of job_queue_processes and some of them expire, these jobs will be postponed to the next polling period. Therefore, you are advised to set the polling interval (the Interval parameter of the submit interface) based on the execution duration of each job to avoid the problem that jobs in the next polling period cannot be properly processed because of overlong job execution time.

Note: If the number of concurrent jobs is large and the value is too small, these jobs will wait in queues. However, a large parameter value leads to large resource consumption. You are advised to set this parameter to 100 and change it based on the system resource condition.

Default value: 10

enable_prevent_job_task_startup

Parameter description: Specifies whether to start the job thread.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: Boolean

  • on indicates that the job thread is not started.
  • off indicates that the job thread is started.

Default value: off