HVR Jobs Don't Load and the REST API Returns a 504 Gateway Timeout Error

Issue

The HVR Hub UI doesn't display jobs, and a GET request for job status returns the following error:

504 Gateway Timeout

Environment

HVR 6

Resolution

To resolve this issue, complete the following steps:

Identify the affected job

Query the HVR repository database to locate jobs configured with invalid trig_crono values. For PostgreSQL, run the following query. Replace <schema> with the schema name:

SELECT hub_name, job_name, attr_arg1
FROM <schema>.hvr_job_attribute
WHERE attr_name = 'trig_crono'
  AND (
        attr_arg1 ~ '(^|[[:space:]])(30|31)[[:space:]]+2([[:space:]]|$)'
     OR attr_arg1 ~ '(^|[[:space:]])31[[:space:]]+(4|6|9|11)([[:space:]]|$)'
  );

For Oracle, SQL Server, or MySQL, adapt the regular expression syntax.

Correct the job schedule

For each affected job, use the returned hub_name and job_name values with the hvrjobconfig command to set a valid schedule. For example, the following command schedules the job for midnight on February 28:

hvrjobconfig -A "trig_crono=0 0 28 * *" <hub_name> <job_name>

Verify the UI

Refresh the HVR Hub UI or repeat the GET API request to confirm that the job list loads without timing out.

Cause

This issue occurs when a job's trig_crono attribute is set to an invalid cron expression that specifies an impossible calendar date, such as 0 0 31 2 * (February 31).

When we evaluate a non-existent date, we repeatedly advance the year while searching for a matching leap year. Since the date never occurs, the thread hangs indefinitely. When the job status query hits the configured API response timeout, the gateway terminates the request and returns a 504 Gateway Timeout error.