database - Can this strange behaviour be explained by Eventual Consistency on the App Engine Datastore? -


i have implemented 2 server-side http endpoints 1) stores data , 2) processes it. method 1) calls method 2) through app engine tasks since time consuming tasks not want client wait for. process illustrated in sequence diagram below.

now time time experience processing task (named processsomething in sequence diagram below) can't find data when attempting process - illustrated yellow throw wtfexception() below. can explained eventual consistency model described here?

the document says strong consistency reads eventual consistency writes. i'm not sure means related case. clarification appreciated.

enter image description here

edit: realize i'm asking boolean question here, guess i'm looking answer backed documentation on eventual consistency in general , on google datastore

edit 2: request here details on actual read/write operations:

the write operation: 

entitymanager.persist(hand);  entitymanager.close()

i'm using jpa data persistance. object 'hand' recieved client , not stored in db new key id assigned.

the read operation: 

select p hand p p.gameid = :gid , p.roundno = :rno

neither gameid nor roundno primary key. gameid "foreign key" although datastore oblivious of design.

it if showed actual code, showing how save entity , how retrieve it, assuming id actual datastore id, part of key, , load get using id , not query on other property eventual-consistency not issue.

(the documentation on further down page linked.)


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