- Another crontab for executing recurring tasks
- Only one task with the same name can exist at a given time
- bash
- sleep usleep bc cut
- php-cli
# See example.ini
vim mytasks.ini
chmod x crond.sh
crond.sh start mytasks.ini- Single Machine, Multiple Applications
- Due to centralized deployment, several projects (php/slim, php/webman, go/somer, go/ginping, python/kingpin X2) are deployed on the same machine. Of course, not all of them are docker containers; the tasks come in various flavors.
- Why not separate deployments? The machine has 32 cores and 64GB memory, which might not be attainable in a cloud service.
- Insufficiency of crontab
- Cron does not care if the previous run of the same task has completed when a new instance starts. When a task starts, I want the previous one to have completed and exited.
- Crontab has another issue. When NTP synchronized time exceeds 1 second, the scheduled tasks will no longer run.
- Solution from a Decade Ago
- Perhaps supervisor is more suitable, but the configuration is relatively cumbersome.
- Digging out a solution from ten years ago, utilizing bash while loop to control the loop, with some modifications it works fine. Let's go with it.