Project Newman :: The scheduler

August 26th, 2006

Now that we've covered the reporter, the editor and the publisher, we have a functional Newman that can actually post stories. I set up Newman to run in a cron job (ie. at set intervals) to run every three hours, but then it occurred to me that it isn't human behavior to post at 9am, then at 12am, then at 3pm and so on, it just doesn't look real. And if someone were to keep an eye on Newman, they might notice that it always posts at regular intervals, which looks odd. (The point here isn't so much to fool people into believing that Newman is real, it is just to make it so that it seems to exhibit a lot of human qualities.)

So I thought why not add a scheduler to decide when Newman should run. The scheduler runs as a daemon (ie. an application that runs 24/7 in the background, but only does actual work whenever it is called upon). So the scheduler is given a time interval (for instance: 3 hours), and then it generates a random number between 0 and 3 hours. That's when Newman is going to run. And then it goes to sleep until that time. So if I start the scheduler at 10am, give it an interval of three hours, it may decide that Newman should run at 11.45. So then it goes to sleep until 11.45 and then it runs Newman.


The advantage of this method is also that if the scheduler runs Newman and Newman crashes, it won't make the scheduler crash. So the scheduler will still keep running and will again run Newman at the next interval. I've also made sure that the scheduler waits for Newman to finish, so that if Newman is taking a lot time to complete and the next interval is in 5 minutes, Newman will not be started again until the current execution is finished.

This entry is part of the series Project Newman.

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