Deferred scheduling

You can create a job with delayed and recurring execution. Let's focus on the options in the next sections.

Delayed execution

To delay the execution of a Job, specify deferred_until argument.

from datetime import datetime

from repid import Job

# code above is omitted

Job("delayed_job", deferred_until=datetime(2077, 1, 1))  # (1)

# code below is omitted

The job will be executed on the 1st of January in 2077.

Recurring execution

Warning

Next execution time for a recurring job is set after the previous execution. Therefore, if a job wasn't processed or processing took longer than recurring time frame, next execution will be set to the next earliest time.

Defer by

If you want a job to be executed every equal period of time (e.g. every 10 minutes, every 2 days, etc.) you can specify deferred_by argument.

from datetime import timedelta

from repid import Job

# code above is omitted

Job("every_2_days", deferred_by=timedelta(days=2))

# code below is omitted

cron

If you want to specify a job with recurring execution in cron format, you will have to install repid with additional flag as follows:

pip install repid[cron]

It will install croniter package, which will be used internally to calculate next time of an execution.

You can specify any cron string supported by croniter using cron argument of a Job.

from repid import Job

# code above is omitted

Job("every_day_at_noon", cron="0 12 * * *")

# code below is omitted

Rescheduling and retries

Rescheduling for a retry will take precedence over rescheduling for the next recurring iteration.

Keep in mind, that depending on the way how your retries are set up, some recurring iterations might be skipped.

If the number of retries was exceeded the job will be rescheduled for the next recurring iteration anyway.

Combining

Combining deferred_by and cron in one job is prohibited.

Combining deferred_until with either deferred_by or cron will delay the first execution until deferred_until and recurrently continue using deferred_by or cron.

Time-to-live

You can narrow the time of message consumption window using ttl argument. It will ensure that since latest scheduling hasn't passed any more time. If not, the message will be marked as 'not acknowledged' and put in a dead-letter queue.

from datetime import timedelta

from repid import Job

# code above is omitted

Job("consume_me_faster_than_3_days", ttl=timedelta(days=3))

# code below is omitted

Note

Every rescheduling of a Job resets time-to-live timer. Time of rescheduling will be considered the new starting point.

Recap

Delay job's execution using deferred_until
Create a recurring job using deferred_by or cron
Set ttl to ensure fast enough consumption