Hi,
I'm using SDN 3.1.2 with Neo4j 2.1.2.
I have this (simple) Akka code (a worker actor retrieving new events in a
kind of loop to consume them):
def receive = {
case RetrieveNewEvents =>
val tx = graphDatabaseService.beginTx() //starts transaction
try {
val newEvents = eventRepository.findNewEvents(EventBatchSizeProperty
) //involving @Query("MATCH (e:Event:New) RETURN e ORDER BY e.occurredOn
LIMIT {0}")
newEvents.foreach {
event => {
log.info("sending event: " + event.id + " to eventStream")
context.system.eventStream.publish(event) // sent event to
consumers - no importance for the issue
log.info("event sent to actors to be consumed !")
eventRepository.flagAsConsumed(event.id) // involving
@Query("MATCH (e:Event {_id: {0}}) REMOVE e:New SET e:Consumed return e")
log.info("event: " + event.id + " flagged as consumed !")
}
}
tx.success() // commit the transaction
}
catch {
case e: Throwable => log.info(e.getMessage)
}
finally {
tx.close() //close the transation
system.scheduler.scheduleOnce(EventListenerScheduleProperty seconds,
self, RetrieveNewEvents) // loop again by sending a RetrieveNewEvents
after 1 second
}
}
I noticed that for some events, I retrieved them more that once (written in
my logs)... as if the transaction was not commited, meaning that the label
was not set to CONSUMED yet.
Obviously, if was not set to CONSUMED before the next loop, it would be
retrieve again since still viewed as NEW.
My question is:
May it possible that tx.success() or tx.close() works...asynchronously?!
It seems absurd but it sounds to be the only explanation I guess for
retrieving more than once the same event.
I tried to update the duration from 1 second to 3 seconds, and now the
whole works without this issue.
Is there an apparent issue in my code that I may ignore? Why timing is
important here?
Thanks a lot,
Michael
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