Use a timer to control the cron job

Presently, we're sending a configurable number of emails per cron, with a default of 200.
The UI for configuring subscriptions_number_of_mails isn't there yet though.

    if ((timer_read('page') / 1000) > (ini_get('max_execution_time') / 2)) {
      break; // Stop once we have used over half of the maximum execution time or exceeds the original number of jobs.
    }

Yes, that's an interesting idea, thanks! Let's see what chx thinks of it...

Please try the attached patch, especially those of you with sizeable "test sites," like introfini. :-)

Every cron run creates a watchdog message like the following:

Subscriptions sent N single and M digest messages in S of T seconds; X queue items left.

I'd like to get an idea of what kind of numbers you're seeing.

(I'll add an option to suppress the watchdog message.)

Has anyone tried this yet?

It's implemented now. There's also a new cron message that will show you the relevant numbers. I'd be interested to see some numbers from those of you who are running 2.0 on big "test sites"...

Also see #233079: status of queuing and cron UI or controls?.