Achieving Per-Second Resolution with Linux Task Scheduling

When working with Linux, you might find that the traditional

cron

daemon has a minimum granularity of one minute, which may not be sufficient for your needs. However, there are several alternatives and workarounds to achieve per-second resolution. In this article, we will explore different methods to schedule tasks with high precision on Linux systems.

1. Using Shell Scripts with sleep Command

One approach is to create a shell script that uses a loop with the

sleep

command to execute tasks at a per-second interval. Here is an example:

#!/bin/bashwhile true do     # Your command here    echo    sleep 1done

To run this script in the background, you can use:

nohup ./your_ 

Note that using this method can lead to missed tasks if the script execution takes longer than one second.

2. Utilizing systemd Timers

If you are using a system that employs the systemd service manager, you can create high-precision timers. Here’s how:

Create a service file, e.g., Create a timer file, e.g., /etc/systemd/system/mytask.timer

ini[Unit]DescriptionMy Task[Service]Startn/ini

ini[Unit]DescriptionRun My Task every second[Timer]OnActiveSec1sOnUnitActiveSec1s[Install] WantedBy/ini

To enable and start the timer:

sudo systemctl enable mytask.timersudo systemctl start mytask.timer

This approach ensures that the task is executed with high precision, as the timer is based on the kernel's timer resolution.

3. Using fcron

fcron is an alternative to

cron

that supports more flexible scheduling, allowing you to run jobs more frequently than once a minute. You can install and configure

fcron to run jobs at a per-second interval.

4. Combining cron with Custom Scripts

If you prefer to use the traditional

cron

but need per-second resolution, you can script a wrapper to execute your main cron job every minute and then have the script handle the per-second execution internally. For example:

# In crontab*/1 * * * * /path/to/a

# In afor i in {1..60} do    bash /path/to/b    sleep 1done

# In bdo whatever you want to happen every second.

Ensure that you handle potential race conditions using lock files or other synchronization methods.

Conclusion

While the traditional

cron

does not directly support per-second scheduling, using one of these methods allows you to achieve similar functionality. If high precision timing is crucial, consider using

systemd timers or dedicated scheduling tools like

fcron.

While firing off multiple jobs into a message queue might be an option, the accuracy would still be dependent on the underlying timers, making it less reliable for precise timing.