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How does a Timer execute


If the environment is down, do lost timers run when the environment comes back online?


The environment runs lost timers when it comes back online.


Every timer in the environment has an entry in a platform table with its Next Run instant:

  • After a timer runs, OutSystems platform uses the configured schedule to recalculate the Next Run. For example, if the timer should run every day at 8AM, the Next Run will be 8AM in the following day.
  • A timer run on demand has a Next Run of now. You can run a timer on demand from the Service Center. A program can run a timer through the Wake<Timer> action.


Every 20 seconds, the platform service Scheduler checks the Next Run instant of all timers. The Scheduler runs any timers that are due, including timers in the past.

By default, Scheduler runs up to 3 timers concurrently for each Front-End. If more timers need to run, they wait for an available time slot.

Use the Service Center, in Service Center > Monitoring > Environment Health, to monitor the execution of timers:

  • Check the column Scheduler in the list of Front-end Servers. Timers do not run if the Scheduler service is not running.
  • Check the Next Run column of the list Timers.

Use the Configuration Tool, tab Scheduler, to change how many timers can run concurrently. You need to access the desktop of the server.