Hi Jeff, If you use Python it will retry 3x. """ The datastore uses optimistic locking and retries for transactions. If the transaction prepared by the function cannot be committed, run_in_transaction() calls the function again, retrying the transaction up to 3 times. (To use a different number of retries, use db.run_in_transaction_custom_retries().) Because the transaction function may be called more than once for a single transaction, the function should not have side effects, including modifications to arguments. """ http://code.google.com/appengine/docs/python/datastore/functions.html#run_in_transaction
Not sure about Java, but they seem to keep things more-or-less consistent. Robert On Thu, Aug 26, 2010 at 23:41, Jeff Schwartz <jefftschwa...@gmail.com> wrote: > Thanks but I wasn't specifically asking about tasks but rather transactions > in general. I'd like to know about retries, when they are done & when they > aren't. I'd also like to know if there is any detailed documentation on the > subject. > > On Thu, Aug 26, 2010 at 7:37 PM, Jan Z/ Hapara <jan.zawad...@gmail.com> > wrote: >> >> FWIW we've seen tasks with 23+ retries and a re-queue time of 19+hrs. >> >> Failure rate: depends on what you mean. Task queue can kill your >> tasks (and requeue them) on it's own, plus there is the failure rate >> of other GAE services. >> >> I'm not sure if we've got a unique use-case on our hands (I think not) >> but we're seeing task queue failure rates of 30-90% for non-trivial >> loads (2-5k tasks being queued up). Failure in this case means a >> retry force by the queue manager - tasks do eventually complete, it >> might just take a lot longer than expected. >> >> J >> >> On Aug 27, 10:58 am, Jeff <jefftschwa...@gmail.com> wrote: >> > When a transaction fails because of contention is it automatically >> > retried and if it is how many times will it retry? Also, can you point >> > me to any docs that detail this & transaction failures in general? >> > Thanks in advance. >> >> -- >> 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-appeng...@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. >> > > > > -- > -- > Jeff > > -- > 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-appeng...@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. > -- 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-appeng...@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.
