Task execution strategy
End time for cron (repeated) task's checks
For users with less than or equal to 80 points, the max end time for created tasks is 7 days later.
For users with more than 80 points, the max end time for created tasks is 30 days later.
The default value of end time input field is 7 days later.
Min intervals between tasks
The minimum interval for timed detection tasks is 10 minutes.
When the above conditions are not met, the Create Task page will give a prompt and the Create Task button will be grayed out and cannot be clicked.
a screen capture：
Also, since we need 15 minutes to assign tasks to different servers, the first timed detection task within 15 minutes will be ignored.
Time limit for a single detection task
The time limit for a single detection task is 7 seconds.
For mostly detection tasks, 7 seconds is a reasonable limit and is perfectly adequate.
If we cannot get the web area's text after that time, an error message is reported as
pptr script timeout.
You can see the task's err message in the exported csv file on task list page.
If multiple tasks are all time out, please check our contact information in the top-up page for help.
Email send strategy
If there are multiple changes to the page within a four-hour period, an attempt will only be made to send an alert email on the first change within the four-hour period.
For a web page change, we will try to send an email reminder (if there is already a change reminder email for the same task within four hours, we will not try to send it).
If the reminder email fails to be sent, no further emails will be attempted for this web change, but the next time a change is detected, an alternative email delivery service will be used to attempt to send the reminder email immediately (Not limited to one email in four hours).
If the previous 4 web page change email alerts failed to be sent, only one alert email will be attempted within one hour for the next task.
(To prevent some high-frequency detection tasks from sending frequent emails due to temporary downtime of the mail server, and has no effect on low-frequency detection tasks with intervals greater than one hour)
If the previous 11 times email alerts for web changes are sent failed, reset the number of failed tasks. (then return to the logic in step 1)
The source code is available here. Feel free to submit issues if you have better suggestions.