We are running 1.8.3 We have an instance with ~160 sites that totals ~15,000 visits per day.
For all scheduled e-mail reports, users receive multiple (usually five to twenty) copies of the report all generated at roughly the same time. I have verified that there is only one report record, with only one report type, and for only one site.
My limited understanding of the TaskScheduler leads me to believe that if there are visits between when report generation has started and before the last one has finished, the process might start again?
Did you enable http://piwik.org/setup-auto-archiving/ ?
It is required to achieve reliable task scheduling.
Aha. We had the script running, but it started failing at some point due to php running out of memory. Thanks.