On Tuesday, 12 June 2012 18:24:03 UTC+7, Dao Linh Viet wrote:
>
>
>
> On Tuesday, 12 June 2012 06:20:08 UTC+7, Jeff Schnitzer wrote:
>>
>> Ah, sorry that wasn't clear to me.
>>
>> I'm not sure how the presence of Objectify in this chain could make
>> any difference. There's nothing special about the way Objectify
>> starts or commits a transaction. Was this behavior consistent?
>>
>> Jeff
>>
>> On Mon, Jun 11, 2012 at 8:00 AM, Michael Hermus
>> <michael.her...@gmail.com> wrote:
>> > Jeff,
>> >
>> > There are absolutely no entities being modified or created, so there is
>> no
>> > possibility of data store contention (based on my current
>> understanding),
>> > hence the topic. The only operations during the transaction are Task
>> Queue
>> > inserts. As I said, there is really no reason to use Objectify under
>> those
>> > circumstances so its not really a problem, just something to be aware
>> of.
>> >
>> > Regards,
>> > Mike
>> >
>> > On Sunday, June 10, 2012 11:46:24 PM UTC-4, Jeff Schnitzer wrote:
>> >>
>> >> ConcurentModifcationException happens whenever you have transaction
>> >> collisions. You will often have transaction collisions if you modify
>> >> the same piece of data from multiple tasks.
>> >>
>> >> There are two possible situations here:
>> >>
>> >> 1) "It happens" - sometimes transactions collide. The solution is
>> >> that you should always make transactions idempotent and you should
>> >> always retry them. If you're using Objectify4, doing an
>> >> ofy.transact(new Work() { ... }) will do the retries for you.
>> >>
>> >> 2) You may need to rethink the way data flows in your app. If you
>> >> have a bunch of tasks trying to modify the same piece of data, you're
>> >> going to get a lot of collisions and collisions slow things down.
>> >> Figure out how you can serialize the transactions or combine them.
>> >>
>> >> Jeff
>> >>
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>
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