You'll need to post some more code details - including the structure of the
object you are trying to change. Also you don't mention whether this is an
exception or just a log message. It's easy to accidentally create
contention with the task queue, especially if you're in a transaction and
enqueueing non-transactional tasks (which often start immediately).

Jeff

On Thu, Dec 3, 2015 at 6:14 PM, Yun Li <[email protected]> wrote:

> I am using Objectify. This error happens when updating a single datastore
> entity. There is NO TRANSACTION. My working flow as follows:
>
> 1 Entity entity1 = Objectify.read(id1)
> 2 Modify entity1's property and put "update(entity1)" in a taskqueue
> 3 When task executes: Objectify.save(entity1)
>
> Then I get java.util.ConcurrentModificationException: too much contention
> on these datastore entities
>
> It's so weird because the log shows that even two requests try to update
> entity1, their execution interval could be more than 10s. I am a new GAE
> user, anybody helps me ?
>
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