Jobs using pgagent

Hi....
Iam using postgres since recently.....there are jobs scheduled using the
pgagent. There are loaders and stuff that are scheduled using the pgagent.
There is a new job that i have added............the weird part is that it
runs for different amounts of time everyday. For example: it has run for
3hours,5 hours on some days and for 16hours on some days. It processing
equally amounts of data on each of these days.
When i look at the log file............the RAISE NOTICE statements are not
continous .........i.e. statements of other DB processes are printed and
then the statements of the program are printed............seems like its
running on and off. As far my knowledge goes pgagent can handle parallel
jobs.
Though i see locks made by the program............iam not sure if thats the
problem. Can someone give me a pointer on this?

Thanks
Sam