I've already got these exceptions too, while running mapreduce. I "fixed" this by reducing the rate at which workers were executed.
Here are the issue's details: http://code.google.com/p/googleappengine/issues/detail?id=5608 -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
