Configure the task scheduler [monitors-scheduler]

You specify options under heartbeat.scheduler to control the behavior of the task scheduler.

Example configuration:

heartbeat.scheduler:
  limit: 10
  location: 'UTC-08:00'

In the example, setting limit to 10 guarantees that only 10 concurrent I/O tasks will be active. An I/O task can be the actual check or resolving an address via DNS.

limit [heartbeat-scheduler-limit]

The number of concurrent I/O tasks that Heartbeat is allowed to execute. If set to 0, there is no limit. The default is 0.

Most operating systems set a file descriptor limit of 1024. For Heartbeat to operate correctly and not accidentally block libbeat output, the value that you specify for limit should be below the configured ulimit.

location [heartbeat-scheduler-location]

The time zone for the scheduler. By default the scheduler uses localtime.

job.limit [heartbeat-job-limit]

On top of the scheduler level limit, Heartbeat allows limiting the number of concurrent tasks per monitor/job type.

Example configuration:

heartbeat.jobs:
  http:
    limit: 10

In the example, at any given time Heartbeat guarantees that only 10 concurrent http tasks will be active.

These limits can also be set via the environment variables SYNTHETICS_LIMIT_{{TYPE}}, where {{TYPE}} is one of HTTP, TCP, and ICMP.